16. That city has one of the most ………………. underground rail networks in the world. A. efficient B. fashionable C. cosmopolitan D. fascinated

That city has one of the most ………………. underground rail networks in the world

a) efficient

A

Explanation:

you would most likely hear someone say that a city has an efficient underground rail networks than the rest.

fashionable wouldn't make as much sense because underground rail networks don't have this quality.

cosmopolitan wouldn't work because underground rail networks wouldn't be a group of people

fascinated wouldn't work because no one is being fascinated by it in the sentence

covert: hidden or secret

candid: truthful and straightforward

what i get from these phrases is covert means undercover or underground and that's where the flower is in april. on the other hand, may is the month where flowers start to bloom and thats the reason why candid is being used as a word to describe the blossoming period of a flower.

hope this answer you.