The polymerase chain reaction relies upon unusual, heat-resistant that were isolated from bacteria living in hot springs

The right words to fill the blank are DNA POLYMERASE ENZYME.

Explanation:

DNA polymerase chain is a method used in molecular biology to produce abundant copies of specific DNA segments. The process is catalyzed by an enzyme called DNA polymerase. The DNA polymerase enzyme is usually isolated from bacteria, which live in hot spring. One good example of such bacteria is Thermus aquaticus. The DNA polymerase isolated from this particular bacterium is usually preferred because it is heat stable and produce DNA strands at faster rates compared to natural DNA polymerase.

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.

hello there the answer is d