○ 正解です。

The simplest way to ask somebody to repeat what they said is to say 'Pardon'.

'Pardon' or 'Pardon me' means I'm sorry. It can also be used in other situations, such as if you bump into someone in the street.

'I couldn't catch that' means I couldn't hear that.

People sometimes say 'Eh?' when they can't hear the other person, but this is a little rude.