Which characteristic describes the troposphere? A)contains the ozone layer
B)has the highest air pressure
C)spans 12-50 km above Earth
D)is a good place for planes to fly

It is B)has the highest air pressure

Explanation:

c, a, and d is talking about the straosphere same as a plus plane usally flies above the troposphere cause the altituide is more calmer.

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.

b

is correct hope this   also i learnd this in middle school