71.

Answer and Explanation

Your Answer is

Correct Answer is A

Explanation

The best answer is A because the coordinate adjectives smaller and quicker both modify the noun vessels, and therefore a comma is needed to separate the two adjectives. The order of the adjectives could be swapped to say "quicker, smaller vessels," and it would not change the meaning of the sentence. Likewise, the sentence could say "smaller and quicker" or "quicker and smaller."