Which theory of aging suggests that mechanical functions of the body work less efficiently as people age?

It is the wear and tear theory of ageing.

The wear and tear theory defends that ageing is caused by the damage that happens as time goes by to cells and body systems. The name of the theory reflects this idea of wearing out - the organism is worn out and doesn't function normally. This is the theory that's accepted more generally as common sense but there are other theories of ageing that see the process as a more intentional process.

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.  

the electromagnetic energy from the sun arrives in the form of visible and invisible light.