Question

clear cutting directly affects what in the environment?
air quality and soil erosion
water toxicity and soil ladening
water cycles and magnetic fields

Explanation:

Clear - cutting (removing large areas of trees) reduces trees that absorb $CO_2$ and produce $O_2$, so air quality is affected. Also, without tree roots to hold soil, soil erosion increases. The other options have non - relevant factors (e.g., magnetic fields, non - related water toxicity/soil ladening to clear - cutting).

Answer:

A. air quality and soil erosion