(Shopkeeper : Customer) , (Doctor : Patient) , (Lawyer : Client) , (Clerk : File)
Option:
Justification: In all other pairs, second is the person for whom the first works to earn money.

(Shopkeeper : Customer) , (Doctor : Patient) , (Lawyer : Client) , (Clerk : File)
Justification: In all other pairs, second is the person for whom the first works to earn money.