I must study my books today as I have to give an examination tomorrow. A. for I have to give B. since I have to give C. as I have to take D. No improvement

The correct answer is: D. No improvement.

The sentence “I must study my books today as I have to give an examination tomorrow” is grammatically correct and conveys the intended meaning clearly. The word “as” is used to introduce a reason or cause, and in this case, it is clear that the speaker must study their books today because they have an examination tomorrow.

The other options are not as clear or concise. The word “for” can also be used to introduce a reason, but it

is often used to introduce a purpose or goal. In this case, it is not clear that the speaker is studying their books in order to give an examination. The word “since” can also be used to introduce a reason, but it is often used to introduce a past event or situation. In this case, it is not clear that the speaker is studying their books because they have already taken an examination. The word “take” is a verb that means to receive or accept something. In this case, it is not clear that the speaker is studying their books in order to receive or accept an examination.

Therefore, the correct answer is: D. No improvement.