Based on the pyramid, which organism(s) provide the most available energy?
a)
predator fish
b)
birds and mammals
c)
insects and zooplankton
d)
phytoplankton and bacteria

The correct answer is option D) phytoplankton and bacteria.

It is because of the fact that with advancement in trophic levels in a food chain or food web, energy is lost by 10%. So, the organism which is at lowest position in a food chain will have the most energy while the one at the top will have the least energy. It means that a primary consumer who feeds on plants will have 10% less energy than plants & a secondary consumer who feeds on a primary consumer will have 10% less energy than the primary one. Plants are at the base position in a food chain and phytoplanktons are microscopic algae which are considered as plants. So phytoplanktons will lie at the base position in a trophic level and they will have most available energy. So the correct answer is option D.

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.