According to the theory of island biogeography, the two main processes controlling the number of species at any given time are…
a. predation and competition
b. migration (including immigration and emigration) and extinction
c. birth and death
d. humans and weather
e. natural selection and catastrophes

b. migration and extinction

Explanation:

The theory of island biogeography states that the main processes responsible for controlling the equilibrium and number of species on an island are migration (immigration and emigration) and extinction. Immigration refers to the new species that colonize the island, while emigration refers to the species that move to another region. Finally, extinction refers to the number of species that have been previously established but get extinct.

the statement is true

answer: ice crystals in air

the water from the water body or another source of water gets evaporated as water vapor as an effect of heat on water. these water vapor rises in the upper layers of the earth atmosphere under high atmospheric pressure. the atmospheric pressure of these water molecules starts to decrease due to the effect of cold air. the invisible water vapor condenses into visible water droplets and ice crystals.these ice crystals and water droplets being less denser than the surrounding air floats on air as clouds.