Plant cells begin synthesizing large quantities of heat-shock ...

[xclash]

Plant cells begin synthesizing large quantities of heat-shock proteins
A) after the induction of chaperone proteins.
B) in response to the lack of CO2 following the closing of stomata by ethylene.
C) when desert plants are quickly removed from high temperatures.
D) when they are subjected to moist heat (steam) followed by electric shock.
E) whenever the external temperature exceeds the threshold where photosynthesis is negatively impacted.

[clippers!]

I chose E and got the answer, hope that helps.