The support the sentence offers to a proposed solution is the following one:
Peer testimonial.
It is said that Lisa, a friend (a peer), uses a certain device which helps her manage her finances when it comes to paying heating bills. Therefore, a solution is proposed by offering a peer testimonial, that is, something a friend does which probably works for him or her and can work for someone else as well.
In linguistics, we recognise many kinds of arguments. In this case, the most accurate would be: peer testimonal. It's not a personal experience because it's not from your own, and you have not experienced it. She (Lisa) is your friend, then it's a peer testimonial.
The trait that best describes his behavior in his interaction with the head chef is d. restraint. Being restraint is a way of controlling over your emotions or behavior.