The sudden rapid movement of an unsaturated cohesive mass of soil, regolith, or bedrock is a The sudden rapid movement of an unsaturated cohesive mass of soil, regolith, or bedrock is a: a) debris avalanche.
b) mudflow.
c) landslide.
d) rockfall.

The correct option is C: landslide

Explanation:

A landslide is a huge amount of land, rocks, and other materials that moves downhill. These land moves are caused by erosion and other strengths that may cause the land to move and fall from a steep hillside. Erosion might cause separation of different material layers, and when a land o rocky layer is separated from its immediately anterior one, gravity causes the fall of these layers.

In general, these land moves are very destructive. They can cover rivers, routs, buildings, among others, putting in danger any kind of life.  

There are other moves very similar to landslides, such as mudflow, avalanche, or rockfall.

Rockfall refers to the fall or big rocks from a precipice or steep hillside.

Mudflow refers to a thick stream of mud and other materials.

Avalanche refers to the collapse of snow and other materials.

they each offer a fresh glut of resources to the organisms that can arrive and exploit them. as individuals and new species continue to appear, they actively and passively alter the environment. competition for shared resources increases, local abiotic and biotic conditions shift, and the relative abundances of species change accordingly. the process is called ecological succession, and it is one of the earliest and most well-known concepts in ecology.

true                                                                                                       true true true true true true