Hector is one of four partners in Cross & Co., a firm of solicitors. Hector orders four new safes from Lock Ltd for the storage of confidential documents, one for the office of each partner in the firm. His three partners all think this an extravagance on Hector's part and an unnecessary expense because each office already has lockable filing cabinets in situ. They seek to cancel the order but Lock Ltd refuses and demands payment. Which of the following best describes the legal position of Cross & Co. here? (a) Cross & Co. are bound by the contract because Hector has explicit authority to make such a contract as a partner of the firm. (b) Cross & Co. are bound by the contract which was made within the implied usual authority of Hector as a partner of the firm. (c) Cross & Co. are not bound by the contract which was made ultra vires to his powers as a partner of the firm. (d) Cross & Co. are not bound by the contract because the majority of the partners in the firm have not agreed to it.