Farmer brown sprays insecticides on his crops to kill insects. several days after spraying, he notices many dead bugs around the pond. that summer, the number of frogs around the pond was lower than ever. the frog population has declined because a) the chemical killed the frogs. b) farmer brown scared the frogs away. c) bugs are the limiting factor for the frogs. d) the chemical spray is a limiting factor for the bugs.

C) bugs are the limiting factor for the frogs.

A limiting factor is the ecological factor which limits the growth, abundance and distribution of the population of the species in an ecosystem. A limiting factor can be a biotic or living factor such as competition, and predation or it can be abiotic or non-living such as natural disaster.

According to the given situation, the frog population decline because the bug population was killed by the chemical spray. The bugs might be the source of food for these frogs. Therefore, the bugs were the limiting factor responsible for the decline of the frogs.  

oxygen = 21% of the atmosphere

nitrogen = 78%

carbon dioxide = 0.1%

argon =0.934%