In the Late Nineteenth and Twentieth Centuries, Several Massive Losses

In the late nineteenth and twentieth centuries, several massive losses of organisms occurred. Bison, passenger pigeons, and many other birds declined rapidly or went extinct. Most deciduous forests and prairies were replaced by agricultural fields. These changes led to

A) an increase in biodiversity, as natural processes sped up to replace the losses.
B) an increase in biodiversity, as citizens spontaneously responded to the losses.
C) the rise of conservation biology, as people became concerned about biodiversity losses.
D) an increase in the number of ecologists, who were needed to study the remaining species.