Which of the following insulate against the cold?

carbohydrates
lipids
nucleic acids
proteins

lipids

fats is known to help protect animals from the cold—and not only by acting as insulation. In the early 1990s, scientists studying mice discovered that cold temperatures trigger certain fat cells, called brown adipose tissue, to release stored energy in the form of heat—to burn calories, in other words

your best option is 5,000 kg

the correct answer is:

a population changes in response to a change in the environment.