A customer tells his broker "Sell my position in ABCD (a NASDAQ stock) and use the proceeds to buy EFGH (another NASDAQ stock)." 
Under the 5% Policy, the customer will be charged a commission or mark-up based on the: 
A. purchase of EFGH only 
B. sale of ABCD only 
C. purchase of EFGH separately; and the sale of ABCD separately 
D. purchase of EFGH and the sale of ABCD combined