Why do scientists use the International System of Units (SI)? A. because the SI is based on the metric system

B. because the tools scientists use only measure in SI units

C. so they can communicate their results without confusion

D. so all scientists are guaranteed to come up with the same measurements
PLEASE HELP

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