Based on the Tables Below,which of the Following ANSI SQL

Based on the tables below,which of the following ANSI SQL commands would return the average customer balance grouped by SalesRepNo? GENERAL SALES DATABASE:
SALESREP

CUSTOMER

A) SELECT AVG (Balance)
FROM CUSTOMER
WHERE SalesRepNo;
B) SELECT AVG (Balance)
FROM CUSTOMER
GROUP BY SalesRepNo;
C) SELECT AVG (Balance)
FROM CUSTOMER,SALESREP
WHERE SALESREP.SalesRepNo = CUSTOMER.SalesRepNo;
D) SELECT AVG (Balance)
FROM CUSTOMER
ORDER BY SalesRepNo;
E) SELECT AVG (BalancE)
FROM CUSTOMER,SALESREP
WHERE CUSTOMER.SalesRepNo = CUSTOMER.SalesRepNo
HAVING SalesRepNo;