Understanding the Sentence and Finding the Error

The question asks us to identify the part of the sentence that contains a grammatical error. The given sentence is:

"He will return in a hour."

We need to examine each part of the sentence to see if it follows standard English grammar rules.

Identifying the Incorrect Usage

Let's look closely at the phrase "in a hour". The word "hour" starts with the letter 'h', which is a consonant. However, when we pronounce "hour", the 'h' is silent, and the word begins with a vowel sound, specifically the /aʊər/ sound. The rule for using indefinite articles ("a" or "an") is based on the sound that immediately follows the article.

• We use "a" before words that start with a consonant sound (e.g., a cat, a dog, a unit - because 'u' here sounds like 'you').
• We use "an" before words that start with a vowel sound (a, e, i, o, u sounds, e.g., an apple, an elephant, an ice cream, an orange, an umbrella).

Since "hour" starts with a vowel sound, the correct indefinite article to use before it is "an", not "a".

Therefore, the phrase "in a hour" is grammatically incorrect. It should be "in an hour".

Analyzing the Options for the Error

The sentence has been broken down into the following parts as options:

1. He will
2. in a
3. hour
4. return

We need to find which of these options contains the error we identified.

• Option 1: "He will" - This part is grammatically correct. "He" is the subject pronoun, and "will return" is the future tense verb phrase.
• Option 2: "in a" - This part contains the article "a" which is incorrectly used before the word "hour" in the original sentence. The error lies in the combination of "a" and the subsequent word's sound.
• Option 3: "hour" - The word "hour" itself is spelled correctly and is a valid English word. The error isn't the word itself, but how the article "a" is used with it.
• Option 4: "return" - This is the main verb and is used correctly in the context of the future tense with "will".

Based on our analysis, the error is found within the phrase "in a hour", specifically the incorrect article "a" used before "hour". Option 2, "in a", is the part that includes the incorrect article that makes the phrase wrong when combined with "hour".

The corrected sentence would be "He will return in an hour."

Conclusion

The option that contains the error is the one with the incorrect article "a" being used in anticipation of the word "hour".

The correct option identifying the error is "in a".

Revision Table: Indefinite Articles 'A' vs 'An'

Additional Information on Article Usage

Indefinite articles "a" and "an" are used with singular, countable nouns when the noun is general or being mentioned for the first time. The choice between "a" and "an" depends purely on the sound of the word that immediately follows the article, not the letter it starts with.

Common words that start with a consonant letter but a vowel sound (requiring "an"):

• hour
• honest
• honor / honour
• heir

Common words that start with a vowel letter but a consonant sound (requiring "a"):

• university
• uniform
• union
• European
• one (starts with a /w/ sound)

Understanding the sounds is crucial for correct article usage in English grammar.