Question

Where do birds get energy ___(4)___ such long flights?

• A. of
• B. for
• C. with
• D. at

Answer 1

The correct option is B for

Option B 'for' means 'for the sake of', it refers to purpose. In the given sentence the purpose referred to is 'long flights'. Therefore for is the the correct form of preposition to be used here.

Option C 'With' means 'accompanied by someone', the meaning isn't relevant here.

Option D 'At' refers to time or place.

Option A 'Of'is used to indicate possession, relation, cause, freeing from or about.

Option B is the correct answer.