Complete the sentence with the most suitable option:
It is a pity you drink too much.
If only you ______ so much.
A. Don’t drink
B. Won’t drink
C. Didn’t drink
D. Hadn’t drunk

Hint: Conditional sentences are statements discussing known factors or hypothetical situations and their consequences. Complete conditional sentences contain a conditional clause (often referred to as the if-clause) and the consequence. Consider the following sentences:
Example: I would travel around the world if I won the lottery.

Complete step by step answer:
To know the correct answer let us analyse each option individually.
Don’t drink- This is in present tense. Hence it’s not the correct answer. We are talking about a consequence that is caused by an already happened event.
Won’t drink- Again, this option is in the future tense, it is not appropriate in the above given sentence.
Didn’t drink- This option is in simple past tense, hence it fits appropriately in the sentence.
Hadn’t drunk- As we already know option C is the correct option hence this option is invalid and also it is not in simple past tense.

So, the correct answer is “Option C”.

Note:
In this given sentence, a situation is already declared, “It is a pity you drink too much.”, the following condition ‘if only’ depicts a situation which is wished to be true, so that the present situation could be different if the condition was true. The condition ‘if only’ depicts a hypothetical situation of the past, so it will be followed by simple past tense. Example: I have become so fat, if only I didn’t put on so much.