Both answers are correct.

Also to add since I used to be a FF/EMT, the seatbelt tensioner (the explosive part) most likely will stretch the seat belt as it pulls you back into the seat. Somewhat like a rappelling emergency rope, it's only designed for one-time use and doesn't have the same strength after that. When I was with the company we actually had tags that we stapled onto the seat belt stating you had to get them replaced before you could legally drive it again.

They'll probably replace everything which is expensive since it involves breaking it down to the bare frame of the B post ( right by your head if you're driving).

It's just my 2 cents, but it's not something to be taken lightly since the next accident the seatbelt could tear or break-apart.