I know but this time I ___ it.

Certainly! Let's break down the explanation for the correct choice using the rules of verb tense and form:

গ. mean

Explanation:

1. Present Tense for Current Intent:

- Rule: The present tense is commonly used to express current intentions, statements, or actions.

- Application: In the sentence "I know but this time I mean it," the speaker is indicating a current intention or commitment, making the present tense form "mean" appropriate.

2. Consistency in Tense:

- Rule: It is important to maintain consistency in the tense used within a sentence.

- Application: The choice "mean" aligns with the present tense form used earlier in the sentence ("I know"), ensuring overall consistency.

3. Future Intent with "will" is Not Appropriate:

- Rule: The future tense (using "will") is not suitable in this context because the speaker is expressing a current intention, not a future one.

- Application: Options ক, খ, and ঘ all involve past or future tenses, which do not fit the context of expressing a current intention.

4. Past Perfect (had meant) is Not Necessary:

- Rule: The past perfect tense is used to indicate an action that occurred before another past action. It is not necessary in this context.

- Application: Option খ ("had meant") suggests a past action that is not in line with the meaning of the sentence, where the speaker is expressing a current intention.

Therefore, the correct choice (গ. mean) adheres to the rules of using the present tense to express a current intention, ensuring consistency and clarity in the sentence structure.