What is missing from the co-accretion theory of lunar formation? an explanation accounting for the spherical shape of the moon. an explanation accounting for the origin of the material that makes up the moon. an explanation accounting for the differences in density between the earth and moon. an explanation accounting for the presence of iron in the moon.

the answer is true when observing or determining population size, a direct observation is use, in which each organism is counted in a population or in an area. one benefit of this measure is that you get the exact population count but it will take a long time to  determine  the  size  of a  population.

i think its both a and b

a bird that nests only in a particular tree species.