It is high time we (give up) smoking.

- It is high time, it is time, wish, fancy ইত্যাদি থাকলে Verb এর past form হয়। 
তাই সঠিক উত্তরটি হবে - It is high time we gave up smoking. 

Source: Advanced Learner's English Grammar & Composition by Chowdhury & Hossain.