State at least four (4) types of
biological association.

mutualism - a mutually beneficial symbiotic relationship.

commensalism - a one-sided symbiotic relationship.

parasitism - one species lives on, in or with a host species.

competition - relationship in which organisms compete for resources.

Explanation:

the speed increase from w to x due to increased gravity force

the speed decreases from x to y due to decrease in gravity

correct answer is option a.

tropopause, stratopause and mesopause have all in common aspect that is point of maximum temperature in its layer of the atmosphere. all layers of atmosphere observe abrupt change in temperature. tropopause is the boundary between troposphere and stratosphere. stratopause is the boundary between stratosphere and mesosphere. mesopause is the boundary between mesosphere and thermosphere. these all boundaries are ranges between altitude of 0 to 80 km.