Answer:
Red blood cells and the heart causes response to stimuli
It appears that some of the answer choices got cut off in the image. In any case, thermal energy would flow from a higher-temperature cube to a lower-temperature cube.
So the correct answer should be among the following formulations:
Cube #1 to Cube #3
Cube #2 to Cube #1
Cube #2 to Cube #4
Cube #4 to Cube #3.
Microscope
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