Which best describes the factors that affect a phenotype? a. phenotype is only controlled by the genotype. b. the phenotype is determined only by the environment. c. nutrition is the only thing that determines the phenotype. d. the genotype and the environment both affect phenotype.

D. The genotype and the environment both affect phenotype.

Explanation:

Phenotype is the outward expression  or make up of an organism. The phenotype is simple the physical outlook of an organism. It is as a result of the combination of two major factors which are the genetic make up(genotype) and the environment. When both combines, an organism's pheontype is built and produced.

If the environment is lacking, a gene might not successfully express itself in an organism. Also, an organism might have the right environment but the gene is lacking.

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.