Why is oxygen considered to be an element in the atmosphere but a compound in Earth and in the ocean?

The development of_ factored in the development of complex organisms.

The number of living organisms in a particular area is

Why does meiosis produce cells with half the chromosomes? o a. most of the chromosomes are not necessary to keep an organism alive. b. a gamete needs only half the number of chromosomes because two gametes join together. o c. it makes the gametes easier to move around in the organism. o d. it is faster to produce gametes with fewer chromosomes.