Which sentence uses words with negative connotations?

a. the city streets in the summer are lively and fun.
b. the city streets in the summer are bustling with life.
c. the city streets in the summer are crowded and sticky.
d. the city streets in the summer are full of energy.

The answer happens to obviously be letter C and here is why, a connotation is a choice in words in a form of literature that can give a stronger feeling to the sentence. For example instead of saying scary i could say horifying and that would be a stronger, negative connotation of fear, based on the fact that c is the only negative one, "Crowded and sticky."