walking can make people become more aware of their surroundings,_ the cleanliness of the environment, and the friendliness of the neighborhood.

Incomplete question. The full question reads:

Walking can make people become more aware of their surroundings the cleanliness of the environment, and the friendliness of the neighborhood.

A. consequently

B. despite

C. unfortunately

D. such as

D. such as

Explanation:

By reading through the sentence more carefully we discover it is missing a phrase that would complete the thought been expressed in the sentence.

The correct phrase that rightly completes the thought captured in the sentence is "such as". By using this phrase, readers can note some examples of how people can become more aware of their environments such as the cleanliness of the environment, and the friendliness of the neighborhood.