Sympatric speciation:

only occurs in bacteria.
occurs whenever a physical barrier between two species is removed (i. e., a river dries up) and the two species start to interbreed.
can occur instantaneously through formation of polyploid offspring.
whenever hybrids mate with parental species.
can occur instantaneously through formation of polyploid offspring.

can occur instantaneously through formation of polyploid offspring.

Explanation:

In Sympatric speciation, species are not geographically isolated but reproductively isolated from each other as two varying types of species is observed to have emerged from one original. Take for example, in Fruit Flies where each species have different food choices, making each one to feed on separate fruits.

"SYMPATHETIC SPECIATION do occur instantaneously through formation of polyploid offspring (it has double the normal amount of chromosomes)". And it's most likely take place due to natural selection. It relies on the process of disruptive selection acting against hybrids.

the answer is:

carbon dioxide

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.