"As distance increases, the background becomes more blue with atmospheric haze and reduces in contrast" is the definition of
O foreshortening
linear perspective
atmospheric perspective
O isometric perspective

Atmospheric perspective

Explanation:

A hint to this answer is in the question itself, mentioning "atmospheric haze" but aside from that the definition of atmospheric perspective matches this question. For things like this in the future, it helps to google the definition of each phrase and compare which is the most similar.