Plz help! I will give out BRAINLIEST for best answer

Which of the following is required of a new drug?me

How does food concentration affect yeast activity

Choose the best definition of allele. a. one of several possible versions of a gene, which each produce a different phenotype b. an organism that's purebred for a given trait c. the process of fertilizing a plant with pollen from another plant d. a set of genes that are located on the same chromosome and so are tightly linked