Which term is defined as masses of rock, earth and/or debris that flow downhill. A. tsunami
B. aftershock
C. liquefaction
D. landslide

The term that defines masses of rock, earth and/or debris that flow downhill is landslide (option D).

Explanation:

When a landslide occurs, a certain amount of the mass of earth is detached or displaced downwards, due to the instability present in a certain area, especially when there is a slope in that land or slope .

The area that is unstable is usually in proximity to a stable ground zone, over which the slide occurs. The instability produced by the phenomenon is due to the fact that this ground has reached its maximum tangential tension.

In a landslide, the movement of rocks, debris and everything in the strip of land that slides can also be observed.

The other options are not correct because:

    A. Tsunami is the term for tidal wave, which impedes the displacement of large bodies of water, like waves, that reach the continent.

    B. Aftershock is the term that defines the seismic movements after an earthquake.

    C. Liquefaction of the earth implies that a compact terrain loses strength and becomes semi-liquid.

as resources become scarce because of population growth, the growth decreases after few years due to lack of resources and food.