Each key on a touch-tone telephone makes a slightly different sound when touched. this difference is due to the pitch of sound produced by each key. the difference in pitch is determined by the of the sound waves coming from each key.

Frequency

Explanation:

It s actually the frequency of the sound waves which as perceived as pitch by our ears. Some sound waves vibrate more and hence the pitch is more and some vibrates less and the pitch is less.

The more the oscillation is the higher is the pitch and lesser the oscillation the lower is the pitch which gives us the differences.

the answer would be 2

since they are only saying that the couple has 20 daughters and so on but they never said that they went to the movies as well therefore the couple was the only people that went to the movies.

hope this ! : 3