In some tropical mountains,ecologists have noticed bird species diversity declining in recent years despite seeing normally low elevation species beginning to appear in higher elevations.They blame climate change and increasing temperatures.What might be going on?

A) As temperatures increase, upper elevation conditions become increasingly favorable to lower elevation species.
B) Increasing temperatures at high elevations are driving high elevation species lower to seek cooler temperatures.
C) Lower elevation species are moving up the mountain and out competing the species traditionally found there.
D) As temperatures decrease, upper elevation conditions become increasingly favorable to lower elevation species.