Answer:
B. Taking a friend to lunch in return of a favor
Step-by-step explanation:
Barter System is direct commodity/ service to commodity/service exchange , without using money as an intermediary exchange medium . It is also called C to C exchange .
Eg : Two farmers exchanging their wheat & rice , A teacher teaching grocers' child in exchange of groceries from him .
So : A. Simple Investment , C. Money Purchase , D. Money Denomination exchange - neither are examples of Barter System .
B . Paying off a friend's favour in exchange of a service (being service-service exchange) is a relatable example.