If you answer this correctly ill give you brainliest (HINT IT'S NOT D)

 I believe the answer is A - the total growth of the plants.

in chemistry, a solution’s concentration is how much of a dissolvable substance, known as a solute, is mixed with another substance, called the solvent. the standard formula is c = m/v, where c is the concentration, m is the mass of the solute dissolved, and v is the total volume

answer: they produce more slow than unicellular organisms.