The question asks us to choose the best option to replace the underlined part "has sent" in the sentence: "Gayatri informed one of the directors that she has sent the material for printing."

This sentence involves reported speech (also known as indirect speech). When we report what someone said, the tense of the verbs often changes, especially if the reporting verb (like 'informed', 'said', 'told') is in the past tense. In this sentence, the reporting verb is "informed," which is in the past tense.

Let's look at the original clause being reported: "she has sent the material for printing." The verb here is "has sent," which is in the present perfect tense.

When the reporting verb is in the past tense, the present perfect tense in the direct speech usually changes to the past perfect tense in the reported speech.

• Direct Speech (implied): Gayatri said, "I have sent the material for printing."
• Reporting verb: informed (past tense)
• Verb in direct speech: have sent (present perfect)
• Reported Speech: Gayatri informed... that she _____ the material for printing.

According to the rules of tense shift in reported speech, the present perfect "have sent" changes to past perfect "had sent".

Let's examine the options:

• Option 1: sends - This is the simple present tense. This would be used if the reporting verb were in the present tense or if the reported statement was a universal truth or habitual action (neither applies here). It is not the correct shift from present perfect.
• Option 2: had sent - This is the past perfect tense. This is the correct tense shift from the present perfect tense ("has sent" or "have sent") when the reporting verb ("informed") is in the past tense. This indicates an action that was completed before the reporting action.
• Option 3: had been sending - This is the past perfect continuous tense. This tense is typically used to report the present perfect continuous ("has been sending") or sometimes the simple past ("sent") if the duration is emphasized. The original "has sent" implies a completed action, not an ongoing one, so the continuous form is inappropriate here.
• Option 4: shall be sending - This relates to the future tense. The original statement was about a completed action ("has sent"), not a future one. Therefore, this option is incorrect.

Based on the rules of tense changes in reported speech with a past tense reporting verb, the present perfect "has sent" correctly shifts to the past perfect "had sent".

Revision Table: Reported Speech Tense Changes

The table above summarizes the common tense changes when converting direct speech to reported speech, assuming the reporting verb is in the past tense. Our case involves the Present Perfect shifting to Past Perfect.

Additional Information on Reported Speech

Apart from tense changes, other parts of the sentence may also change in reported speech when the reporting verb is in the past tense. These include:

• Pronouns: Pronouns often change depending on the speaker and listener.
• Time and Place Adverbs: Words indicating proximity in time and place usually change to words indicating distance. For example, 'now' becomes 'then', 'here' becomes 'there', 'today' becomes 'that day', 'tomorrow' becomes 'the next day', 'yesterday' becomes 'the previous day', 'this' becomes 'that', 'these' becomes 'those'.
• Modals: Modals like 'can', 'may', 'will' typically change to 'could', 'might', 'would'. Some modals like 'could', 'would', 'should', 'might', 'ought to' usually do not change.

However, sometimes tense shift does not occur, even if the reporting verb is in the past. This happens:

• If the reported statement is still true at the time of reporting.
• If the reported statement is a universal truth or a fact.
• In certain conditional sentences.

In our sentence, "Gayatri informed... that she has sent...", the action of sending the material is a specific past event relative to the time of informing. Therefore, the standard tense shift rule applies.