Answer: that.
Explanation: A relative pronoun is a type of pronoun that often introduces dependent (or relative) clauses in sentences. They also can be the subject or object of a sentence. The relative pronouns are who, whoever, whom, whomever, that, which, when, where, and whos. In the given sentence we can see an example of a relative pronoun in the word "that," it introduces the relative clause "that have the strongest talons."