Which of the following is an example of a behavioral mechanism used by an ectotherm when the ambient temperature drops?
-basking on black rocks
-developing dark or black coloration to increase heat absorption
-reducing heart rate during cold periods
-hiding under foliage

basking on black rocks.

Explanation:

In ectotherms, your body temperature depends primarily on external heat sources. The temperature of the ectotherms increases or decreases in conjunction with the temperature of their environment. Despite the fact that ectotherms produce some metabolic heat, they cannot increase their heat to maintain a specific internal temperature.

On the other hand, ectotherms regulate their body temperature, but seek sun, shade, etc. to search for environments whose temperatures compensate your needs.

not sure if this what   you'r looking for would be percent composition