Magnetic reversals
a. cause the movements of tectonic plates
b. confirmed the existence of subduction zones
c. provide strong evidence for seafloor spreading
d. have never occurred during geologic time

The answer is C.

Seafloor spreading occurs at diverging tectonic plates boundaries (such as at mid-ocean ridges). When magma upwells to fill up the void, the iron in the magma aligns itself with earth’s magnetic fields  before the magma cools to new crust. Since earth's north and south switch polarity over several centuries, the iron in newly formed crust will align opposite from the previously formed crust. These reversals can be used to prove that the bands of the new crust were laid at different times.

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.

1. a tropical dry forest carries out more rapid nutrient cycling