In the Section "Investigating Life: Two Kingdoms and a Virus $\circ$

In the section "Investigating Life: Two Kingdoms and a Virus Team Up to Beat the Heat",what is the dependent variable in the figure?

A) number of plants that could grow at 37 ^$\circ$ C
B) number of plants that could grow at 65 ^$\circ$ C
C) number of plants that died at 65 ^$\circ$ C
D) number of plants that died at 37 ^$\circ$ C
E) None of the answer choices is correct.