Two astronauts are 4.0m apart in their spaceship. One speaks to the other. The conversation is transmitted to earth via electromagnetic waves. The time it takes for the sound waves to travel through the air between the astronauts (v _sound = 333 m/s) equals the time it takes for the electromagnetic waves to reach earth. How far away from earth is the spaceship?

a. 1.3 x 10⁶ m

b. 1.7 x 10⁶ m

c. 3.6 x 10⁶ m

d. none of these