Answer:B. “He is the tallest.”
Explanation: with the usage of answer B in placement of the sentence, it would look like “Back then, his height was less than mine, Now, he is the tallest”, options A, C, and D are incorrect as they don’t correctly form a comprehensive sentence, while answer E, granted makes sense in a sentence, doesn’t work as it’s telling you someone became older but got shorter, this is common sense to be incorrect unless the subject is elderly, which doesn’t seem to be the case.