Question

complete the sentence with the best relative pronoun. guion s. bluford was a pilot in the u.s. air force later became an astronaut and, in 1983, was the first african american to travel in space aboard the space shuttle challenger.

Explanation:

In this sentence, the relative pronoun is used to refer to "Guion S. Bluford" (a person). The relative pronoun "who" is used to refer to people in a relative clause.

Answer:

who