How do carnivores (which eat only meat) obtain nitrogen for building critical organic molecules?
A) They eat consumers, which ate plants, which absorbed it from the soil.
B) They absorb the nitrogen in the ground through their skin.
C) They have special cells, which filter nitrogen out of the water they drink.
D) They find nitrogen rich soil and lick it to dissolve the nitrogen in their saliva.

Option A is correct. They eat consumers which ate plants, which absorb it from soil.

Explanation:

Carnivores get nitrogen from the food they eat or consuming nitrogen from the small insects trapped in plant. They eat consumers which in turn eat plants and absorb nitrogen from the soil.

answer: substrate concentration. enzymes work best when there is a high enough substrate concentration for the reaction they catalyse.