What is the black/dark material that is visible in many of these onion cells? A. roots
B. DNA
C. cell membranes
D. hair​

C. cell membranes

Explanation:

the black/dark material that is visible in many of these onion cells is cell membranes.

all answers true and false

explanation:

the most common energy conversion is from kinetic energy to potential energy, and then from potential energy to kinetic energy.

later on comes the heat energy, mechanical energy, and other energy conversions.

this energy conversion is so common that we can find it in our day to day lives as well.

- one of the most common energy conversions involves the changing of potential energy to kinetic energy or kinetic energy to potential energy