What characteristics do only primates, rodents, and
rabbits have?

Answer:

Primates, rodents, and rabbits all are mammals which come under the subclass Eutheria of class Mammalia.

Explanation:

Class Mammalia is divided into three subclasses those are Eutheria, Metatheria and Prototheria. Eutheria consists of animals that give birth to young ones for example all the primates, rodents and mammals like rabbits. Metatheria consists of the animals that give birth to immature babies which will live in the pouches of their parents for example Kangaroo. Prototheria includes those mammals which lay eggs for example Platypus.

any abiotic or biotic factor in an ecosystem that causes a population's size to slow or decrease is a limiting factor.

well for one plants are always the producer, so a is the answer. a wolf is more of the consumer(predator) and the deer is the prey so i know those two are out of the question. also mushrooms are fungi/fungus so a is the producer.