Two astronauts are working outside their spacecraft in open space, where there is a vacuum. Astronaut X strikes a metal rod with a hammer while still holding the rod. Astronaut Y is floating 2m away and is not touching the rod or any part of the spacecraft. Which of the following best describes what each astronaut will hear?
a) Neither X nor Y hears any sound in this situation.
b) Only X hears the sound, transmitted through the rod and his glove.
c) Only Y hears the sound, transmitted through the vacuum between them.
d) Both X and Y hear the sound at the same instant.