What are the assumptions that an outsider can make when dealing with an agent of a company? Which of the following is correct?

An outsider is entitled to assume that anyone they deal with is properly authorised, irrespective of any suspicions they may have had about that agent's authority.

Under s 128 of the CA only the directors are permitted to authorise any contracts on behalf of a company.

An outsider is not permitted to assume every person who represents a company has authority, an outsider must check on the authority of that person before entering any contract or undertaking.

Under s 128 of the CA and outsider is entitled to make all the assumptions of s 129 as to the authority of the person they are dealing with, and the validity of the transaction.