Structures as different as human arms, bat wings, and dolphin flippers contain many of the same bones, these bones having developed from very similar embryonic tissues. How do biologists interpret these similarities?

By predicting that the organisms have originated from a common ancestor

Explanation:

In the given case, the bones of the arms of the human, the flippers of the dolphin and the wings of a bat are similar in their structure.

This similarity is structure shows that at some point in time they could have shared a common ancestor. Although these structures performed different functions they are similar in their appearance. Such structures are known as homologous structures.

Thus, By predicting that the organisms have originated from a common ancestor is correct.

parasites can detrimentally affect their host, but also must not allow their host to die before they can complete their life cycle. some parasites have complex life cycles with many different hosts, and have had to find ways of persisting in many different environments during the change from one host to another. ectoparasites live outside the body of the host, and can more easily  disperse, but are  more exposed to predators, parasites, parasitoids. endoparasites live inside the body of the host, and are therefore protected from the outside environment. but they can be  attacked by the host's immune system. they have therefore developed  mechanisms for dispersal such as  complex life cycles.

the correct answer is 2 and 4