Mountains that have developed because of compressional stress—colliding plates that force rock layers upward—are called?

a)folded mountains

b)fault-block mountains

c)canyons

d)plateaus

B) Fault block mountains

Happens when two plates collide, and force the rock up.

a) Folded mountains

The correct answer is a) folded mountains.

To understand why folded mountains are the correct answer, let's break down the question and the options.

The question mentions mountains that have developed due to compressional stress caused by colliding plates. This type of stress occurs when two tectonic plates come together and their edges push against each other, causing the rock layers in between to buckle and fold. Based on this information, we're looking for a term that describes mountains formed through this process.

Now, let's analyze the options:

a) Folded mountains: This option directly corresponds to the description we just discussed. Folded mountains are created when stress from colliding plates causes the rocks to fold and buckle, forming mountains. This matches the given information and is the correct answer.

b) Fault-block mountains: Fault-block mountains are formed when large blocks of crust are uplifted and tilted along faults or fractures. This type of mountain formation is caused by tensional stress, not compression. Therefore, it does not match the information given in the question.

c) Canyons: Canyons are deep, narrow valleys with steep sides. They are typically formed by erosion, and their creation is not directly linked to compressional stress and the formation of mountains through plate collisions. Thus, this option does not fit the description provided.

d) Plateaus: Plateaus are elevated flat areas of land, often with steep sides. They can be formed by various processes, such as volcanic activity, erosion, or tectonic uplift. While plateaus can be associated with compressional stress, they are not specifically linked to the formation of mountains caused by colliding plates. Therefore, this option does not accurately describe the situation mentioned in the question.

In summary, by considering the geological process described in the question, the correct answer is a) folded mountains.