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C. predation

Explanation:

The limiting factor that is being displayed when a fox chases a pika is predation.

Limiting factors can be referred to as those features in the environment which actually leads to the limitation in the growth, distribution or availability/abundance of an organism or population of organisms in an ecosystem.

In the predation limiting factor, as the population of the prey decreases, the population of the predator starts to decrease as well. In other words, we can say that one factor limits the growth of the other factor.

cell regulation is conducted by special proteins.

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