Read the sentence and answer the question. in the early years of the space program, astronauts studied three complex subjects rocket engines, flight mechanics, and computer theory. which correctly shows where a colon is needed in the sentence? a. in the early years of the space program, astronauts studied three complex subjects: rocket engines, flight mechanics, and computer theory. b. in the early years of the space program: astronauts studied three complex subjects rocket engines, flight mechanics, and computer theory. c. in the early years of: the space program, astronauts studied three complex subjects rocket engines, flight mechanics, and computer theory. d. in the early years of the space program, astronauts studied: three complex subjects rocket engines, flight mechanics, and computer theory.