Which of the following can be done under Section 117 of Indian Evidence Act?

Option a and b are provided as explanations to Section 117 of Evidence Act Section 117 is Estoppel of acceptor of bill of exchange, bailee or licensee. –– No acceptor of a bill of exchange shall be permitted to deny that the drawer had authority to draw such bill or to endorse it; nor shall any bailee or licensee be permitted to deny that his bailor or licensor had, at the time when the bailment or licence commenced, authority to make such bailment or grant such licence