Bob Gates, aged 16, looks 19. He is also mentally incompetent, but it is not obvious that he is. Bob buys a top of the line computer from a salesperson, who has no idea that he is under age and incompetent. Bob paid $3,800 cash for the computer. On what grounds can Bob cancel the contract?

a.Because he is a minor

b.Mental incompetency alone

c.Because he paid cash for the computer

d.Because he paid cash for the computer&mental incompetence