Bob tries to negotiate with his lender to try and reduce his debt. The lender comes back and says he can pay only the interest as it accrues, and that would reduce his monthly payment.
a) Because he's only paying the interest, his principal balance will go up.
b) As his monthly payments go down, so does his overall debt burden. The lender is being generous.
c) He's still making payments on the loan, and so he will eventually pay it off, albeit slower because his payments are reduced.
d) His principal balance will not change. He'll keep paying the interest until he can pay down on the principal balance as well.