Although He Had No Actual or Implied Authority to Do

Although he had no actual or implied authority to do so,while the owner of Acta Investments was away,her long-time executive assistant entered into a one-year lease contract with a photocopier company.As it turns out,the contract is very favourable to Acta.In which situation would Acta be unable to ratify the lease contract by its "agent"?

A) where the contract favours Acta
B) where the contract favours the "agent"
C) where Acta fails to act within a reasonable time
D) where the "agent" lacked actual authority