In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.

[EX Q]: Cleavage is imperfect in _ directions, prismatically.
[EX A]: two

[EX Q]: Thermal equilibrium occurs when _ bodies have the same temperature.
[EX A]: two

[EX Q]: Sharpness is also a factor of the focus of all _ color elements.
[EX A]:
three