How long would it take a light pulse sent from Earth to reach the lunar reflector and then return to Earth

In 1969, Apollo 11 astronauts placed a special reflector on the Moon. This reflector sends light back in the direction from which it came, regardless of its angle of incidence. With the Moon about 384 000 km from Earth, how long would it take a light pulse sent from Earth to reach the lunar reflector and then return to Earth?

A. 1.28 s
B. 2.56 s
C. 3.85 s
D. 5.13 s

Speed of light = 3 x 10^8 m/s = 3 x 10^5 km/s
Distance = 2 * 384000 km
Time = Distance / Speed = 2 * 384000 / (3 x 10^5) = 2.56 seconds

Answer (B)