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
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