Option 1 states that the men on the Moon can hear the sound but its intensity will be very low. This is incorrect. Since there is no atmosphere on the Moon to transmit sound waves, there will be no sound for the men to hear. Therefore, option 1 is not correct.

Option 2 claims that the men on the Moon can hear the sound of each other in less time than on Earth. However, since there is no medium to propagate sound waves, the concept of time for sound propagation is irrelevant. Therefore, option 2 is also incorrect.

Option 3 correctly states that the men cannot hear the sound of each other on the Moon. This is because without a medium like air or water, sound waves cannot travel and be perceived by the human ear. Therefore, option 3 is the correct answer.

Option 4 suggests that the sound of the men`s voices on the Moon is magnified. However, without a medium to transmit sound waves, there will be no sound to amplify. Therefore, option 4 is also incorrect.

In summary, option 3 is the correct answer as the men on the Moon cannot hear the sound of each other due to the absence of a medium for sound transmission.