Which is the best definition of genetic engineering? variation in an organism's traits by natural variation of its dna modification of an organism's characteristics by maintaining its dna full removal of an organism's characteristics by altering its dna changing an organism's characteristics by manipulating its dna

How does the molecular clock work? a. it analyzes the brain functionality of two different species.b. it examines and compares the physical characteristics of two different species.c. it illustrates relationships between two different species.d. it compares the number of mutations that exist in the dna of two different species.