Answer:
it
Explanation:
It cannot be "them" becasue telephone is singular and them is plural.
It can't be "her" becasue its not a person
It cant be "that" becasue it changes the tense of the sentence
So the only answer left is "it"
The last one I couldn’t see it that clearly but it haves to be the last one
A comma is used to show a short pause in a sentence