Which of the following is an example of a fixed interval reinforcement schedule?

The arctic is a cold deset biome, which one of the answers is not correct? a) animals in cold deserts burrow to get out of the harsh climates. b) vegetation in cold deserts is normally shallow rooted small shrubs. c) animals in cold deserts hibernate most of the year to get out of the cold. d) soils are very heavy and course. e) the region receives less than 10 inches of precipitation annually.