Answer:
proteins, nucleic acids ,and carbohydrates can form from all elements
Explanation:
The trout because the trout affect the population of the frogs so their for if you lower the population of the trout it would raise the population of the frogs and visversa. <span />
Answer: Option A.
Explanation: The correct answer to the question is option A, because not all proteins are made up of some combination of 20 essential amino acids.
It is the variable being controlled/changed to see if there are any effects on the dependent variable (the thing getting tested/measured)