Refer to the Figure

Refer to the figure.
Individual species vary in their response to climate change. What is the best explanation for what is happening to communities in the European Alps as a result of climate change?

A) On mountains with elevations lower than 3,200 feet, existing communities are becoming more species-rich due to the addition of low-elevation species.
B) On mountains with elevations higher than 3,200 feet, existing communities are being displaced by lower-elevation communities.
C) Across all mountains, species richness is increasing because of subalpine species migrating into the alpine.
D) The species richness of the communities with the most historical species richness are increasing the most because they were historically the most resource-rich communities.