Answer:
C. That
Step-by-step explanation:
Hyenas that are rather small animals, are able to get food through cunning.
The text implies that Hyenas are small animals but are able to get their food in a cunning way.
"That" can be a pronoun, an adverb, an adjective and a conjunction. The plural is "those".
"That" as a pronoun is used to indicate a person, an idea, a state, an event, a time and a remark.
That as used in the passage gives indicate what an Hyena is and how it get its food.