How do mutations lead to variation? A.
by producing changes in the genetic code
B.
by giving organisms new features for survival
C.
by providing a source of energy for cells
D.
by signaling proteins to be synthesized

A.producing changes in the genetic code

Explanation:

Genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).

b would be the right answer

only about ten percent of the energy at one trophic level is passed on to organisms at the next trophic level. the remainder of the energy is used in life processes or lost as heat.