It is believed the major reason for the decline in amphibian species is
a. death through disease
b. changing reproductive habits
c. mutation
d. climate change

The right answer is climate change.

Amphibians do not have the possibility of producing heat. Their activity depends on the environmental temperature and its fluctuations. For example, an average temperature increase of 1 ° C is likely to increase the metabolic expenditure of ectotherms by at least 10 to 30%. Global warming has or will have a significant impact on populations and their ability to adapt according to the evolutionary history of species.

b - the respond is innate and varies over time.

good luck!