Choices B, C, D, and E are all incorrect. According to the cladogram, trouts and humans shares a notochord and a backbone with a common ancestor.

A. Notochord

Choices A, B, C, and E are incorrect. Based on the fossil records, the correct order of appearance in the chordate evolution is notochord, backbone/vertebrae, jaws and paired appendages, true bones, lungs, four limbs, amniotic egg, and endothermy.

D. notochord, vertebrae, jaws, bones

Choices A, C, D, and E are incorrect. Hominins developed opposable thumbs that are able to move around and touch other fingertips. This anatomical feature enabled them to touch and grasp objects and tools.

B. Hominins evolved an opposable thumb that enabled hands to grasp objects.

Choices A, B, C, and E are incorrect. In a bee colony, the worker bees are closely related females and they are all sterile. Their main task is to protect their queen bee so it can reproduce more bees. In this way, the genes are passed on to the next generation. This behavior shows the kin selection theory in which closely related individuals ensure the survival of their own species.

D. This behavior increases the chances that genes shared by relatives will be passed to offspring.