Chimpanzees and gorillas are genetically similar, sharing more than 98 percent of their DNA. While they have many of the same body parts, the details of these body parts differ. between the two species. Chimpanzees and gorillas. have a difference of 2 percent in their DNA. sequences, but that difference represents more than 35 million base pairs that differ in the chromosomes of every cell. These base-pair changes account for the physical differences seen between the two species. One difference between the two species is the shape of their hands and feet.   Much like a human hand, chimpanzee and gorilla hands have opposable thumbs. This adaptation is good for picking up small objects and eating with one hand. Chimpanzees have fingers that are much longer and narrower than gorillas' fingers and have thumbs that are slightly smaller and sit farther down on their palms than gorillas' thumbs do. As a result, chimpanzees' thumbs are not as fully opposable as those of gorillas. Gorillas have much wider palms and have thumbs that can rotate more easily than chimpanzees' thumbs. This allows gorillas to pick up objects more easily than chimpanzees can. Both chimpanzees and gorillas have feet with opposable big toes. This adaptation allows them to grasp objects, including branches, with their feet.  Chimpanzees spend much of their time climbing trees, but gorillas spend most of their time foraging on the ground, returning. to the trees only to sleep. Gorillas can stand and move on two legs but can run much faster on all fours.  One reason for the differences in stretches of. DNA called enhancers. Enhancers control the activity of genes. When certain proteins, called activators, bind to enhancers, it causes the DNA to fold and allows other molecules to bind to the DNA. The result is that genes are switched on. If the sequence of an enhancer is changed, the activator will not bind to it. As a result, the DNA will not fold and the gene will not be switched on.  One enhancer sequence, called HACNS1, is thought to control the structure of the hands and feet In chimpanzees and gorillas. Scientists have found that a working version of the enhancer sequence is needed for hand and foot development to take place. They have also found that the chimpanzees contain a mutant, non-working version of HACNS1. Figure 2 models how different versions of HACNS1 behave in a cell. Which statements explain the most likely cause of the difference between the hands of chimpanzees and those of gorillas? Select the three correct answers. Group of answer choices    A/ A single nucleotide base in the enhancer sequence changed, which caused an activator protein to bind to the enhancer sequence.   B/ Several individual chimpanzees all developed the same mutation at the same time, which caused them to grip branches better.   C/ Chimpanzees used their hands for climbing more than gorillas did, so their DNA mutated to disable enhancers and caused their hands to develop differently from those of gorillas.   D/ The exchange of pieces of DNA between alleles during sexual reproduction caused new combinations of DNA to form.   E/ An individual had a genetic mutation that resulted in a hand structure with a selective advantage that was passed on to offspring.   F/ Mutations in the enhancer sequences in chimpanzees resulted in the production of new activator proteins.