Which Two Terrestrial Biomes Are Most Likely to Exist Adjacent

Which two terrestrial biomes are most likely to exist adjacent to one another?

A) (a) periods of little or no rainfall with widely fluctuating daily ambient temperatures and (b) permanently frozen soil layer that prevents deep roots
B) (a) rich biodiversity but poor soils and (b) primarily deciduous trees with seasonal droughts
C) (a) rough, scrubby areas along coastlines and (b) primarily grass-covered with very few trees