Question

one major problem that environmental engineers tackle is: exploring space and planets. increasing the yield of crops. rating the fuel efficiency of cars. removing pollution from the air.

Explanation:

Environmental engineers focus on protecting the environment. Removing air - pollution is an environmental protection task. Exploring space is for space scientists, increasing crop yield is for agricultural scientists, and rating car fuel - efficiency is more related to automotive or energy - related fields.

Answer:

removing pollution from the air