Identifying the Grammatically Correct Sentence

The question asks us to select the sentence that is grammatically correct among the given options. To do this, we need to carefully examine the use of articles ('a', 'the', or no article) and other grammatical elements in each sentence.

Analyzing Each Sentence Option

Let's break down each option and analyze its grammatical structure, paying close attention to the use of articles, especially before "sixth day" and "participants".

1. Option A: "Today is sixth day of our workshop. All the participants are highly enthusiastic."
   • The phrase "sixth day" refers to a specific day in a sequence (the sixth one). Ordinal numbers like 'sixth' when referring to a specific item in a series usually require the definite article "the".
   • So, "sixth day" should be "the sixth day".
   • "All the participants" is grammatically correct here as it refers to a specific group of participants (those in "our workshop").
   • This sentence is grammatically incorrect because of the missing "the" before "sixth day".
2. Option B: "Today is a sixth day of our workshop. All the participants are highly enthusiastic."
   • Again, "sixth day" refers to a specific day in a sequence. Using the indefinite article "a" before an ordinal number like 'sixth' in this context is incorrect. "a sixth day" would imply one out of many possible sixth days, which doesn't fit the context of a single workshop's progression.
   • "All the participants" is grammatically correct.
   • This sentence is grammatically incorrect because of the incorrect use of "a" before "sixth day".
3. Option C: "Today is the sixth day of our workshop. All the participants are highly enthusiastic."
   • "Today is the sixth day of our workshop." - The use of "the" before "sixth day" is correct because it specifies which particular day it is in the sequence of the workshop.
   • "All the participants are highly enthusiastic." - The use of "the" before "participants" is correct because it refers to the specific group of participants attending "our workshop".
   • Both parts of the sentence are grammatically correct.
4. Option D: "Today is sixth day of our workshop. All participants are highly enthusiastic."
   • "Today is sixth day of our workshop." - This part is grammatically incorrect due to the missing "the" before "sixth day".
   • "All participants are highly enthusiastic." - While "All participants" without "the" can be used in general statements, in the context of "our workshop," referring to a specific group, "All the participants" is the more appropriate and common usage. However, the primary error is in the first part.
   • This sentence is grammatically incorrect primarily because of the missing "the" before "sixth day".

Conclusion

Based on the analysis of article usage with ordinal numbers and specific plural nouns, Option C is the only sentence that correctly uses articles in both parts.

Therefore, the grammatically correct sentence is found in Option C.

Revision Table: Key Grammar Points

Additional Information: Understanding Articles

Articles are words like 'a', 'an', and 'the'. They are used before nouns to indicate whether the noun is specific or non-specific.

• Definite Article ('the'): Used to refer to a specific or particular noun that has already been mentioned, is understood from the context, or is unique. It can be used with singular and plural countable nouns, and uncountable nouns.
• Indefinite Articles ('a', 'an'): Used to refer to a non-specific or general singular countable noun. 'a' is used before consonant sounds, and 'an' is used before vowel sounds.
• Zero Article (No Article): Used with uncountable nouns and plural countable nouns when talking about them in a general sense. Also used before proper nouns (names of people, places, etc.), abstract nouns, and in some fixed expressions.

In the question, "the sixth day" is specific because it's a particular day in the workshop's sequence. "the participants" is specific because they are the participants of "our workshop".