Which one of these lines uses iambic pentameter?

A. Honeydew is the worst melon of all melons.

B. Saachi is a good and trusted friend.

C. Generally, fish make for rather tame pets.

D. I put a tree in front of Peter's vase.

D. i put a tree in front of peter's vase

First of all, you need to know what an iambic pentameter is. Iamb refers to the sequence of stressed and unstressed syllables - in this case, the unstressed syllable is followed by a stressed one. Pentameter means that there are 5 meters in one line in a poem - and if you know that one meter consists of 2 syllables, then you will know that a pentameter consists of ten syllables (penta = 5). Thus, we are looking for a line that has 10 syllables in total, and the only option that fits that description is D. Hence, the correct answer is D.