Cancer is a disease that is caused by genetic mutations. Which health professionals are least likely to face risk factor in their work that could increase their chances of cancer?

A. Scientists who work with toxic chemicals

B. therapist who operate radiation machine

C. nurses who treat patients with viral infections

D. researches who study DNA replication

The images show two species of tree frogs in a particular region. the gray tree frogs are adapted to the trees of the woodlands, while the green tree frogs can survive in woodlands or grasslands. the gray frog was abundant in the woodlands. because of climatic changes, most of the trees in the region died, and the woodlands changed to grasslands. in such a case, the . the gray tree frog is closely related to the green tree frog genetically, but they have different mating calls. this suggests that speciation occurred because of .