The increase in the number of black snails can. best be explained by

As far as I know about black snails is the fact that the Black Mystery belongs to the genus Pomacea,  Ampullariidae family. This family is also often called Apple Snail, and it contains a nearly 120 different species of snails. I know that increase in the number of black snails can best be explained by the high teperature in which black snails are. It's the main reason of their reproduction.

option a is correct i.e.

explanation:

in context to the membrane of nerve impulse, the outer membrane of neuron is semi permeable that is only sodium ions can pass through the membrane i.e. smaller ions can pass through the membrane while larger ions cannot pass through it.

answer

crater lake was formed when mount mazama produced a large eruption and collapsed to form a caldera, which then filled with water forming a lake.