Normal stress Choose one: A. is a push (compression) or pull (tension) perpendicular to a surface. B. is a compression exerted equally on all sides. C. occurs when rocks move sideways relative to each other. D. is the reason a balloon collapses when you take it to the bottom of a pool.

Option A, is a push (compression) or pull (tension) perpendicular to a surface.

Explanation:

Normal stress acts towards the surface of the object in inward direction and at 90 degrees to the surface.

Generally normal stresses arises due to the weight of the body or by an external force which Is applied perpendicular to the surface of the object

Pressure is a normal stress that arises due to the weight of the object and compression and tensions are normal stresses as a result of force applied perpendicular to the surface of the object.

Hence, option A is correct