Explain why nonforgeability and nonmutability imply nonrepudiation for digital signatures

What will be an ideal response?

The reason non-forgeability and non-mutability imply non-repudiation is that
a signature, SAlice(M), produced by Alice, is easily verifiable using publicly available infor
mation, and it is computationally infeasible for an attacker to have forged this signature
from scratch or to have transformed a different signature into this one (and have it still be
verifiable for the message M). So Alice must have been the one to produce this signature
and the message M must have been what she was signing when she did this.