What type of fold is this? what type of stress caused this fold?

Anticline fold and Compressive Stress.

Explanation:

From the picture, we can see that there is a fold caused in a mountain where one part of the mountain has covered the other.

Fold mountains are formed from the folding of the earth's crust. However, anticline fold is formed which is seen in the picture and is caused by the compressive stress.

An anticline fold is one which has an arch-like shape while compressive stress is directed inward and produces thrust faults.