Which statement is true about nitrogen and oxygen?
a. they make up about 99.9% of the human body
b. they are both used to make water molecules
c. they are both made of protons, neutrons, and electrons.
d. they both contain no subatomic particles

The statement that is true about nitrogen and oxygen is they are both made of protons, neutrons and electrons.  

Explanation:

Nitrogen and oxygen are important for the survival of life. Oxygen is essential to support respiration and energy deriving process of organisms like human beings.

Nitrogen is the element which is essential for healthy growth of plants. Human body is contains oxygen in the highest percentage.  Oxygen content in human body is 65% and Nitrogen content is 3.2%.Thus they would make up only 68.2% of human body and not 99.9% as given in the first option.

Since oxygen and Nitrogen are elements like every element in the universe are made up of sub atomic particles, Proton, neutron and electron .

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).

answer: decrease

a limiting factor is the one which decrease the abundance, distribution and causes extinction of the population of species in a ecosystem. here, predators including hawks, owls and snakes are the limiting factor for the population of mexican free tailed bat.   although bats are nocturnal animals as they forge for food at night these predators also may remain active during night which can decrease the population of the mexican free-tailed bats. also, these bats eat only one type of insects that are moths. the food can also be a limiting factor as all 400 members are dependent upon same type of food needs that are moths. the decrease in the moth population can cause decrease in population size of the mexican free-tailed bats.

therefore, the scenarios will most likely to decrease the population size of the mexican free-tailed bats.