Bank B's Price Is Shown by a Broker to Bank

Multiple Choice

Bank B's price is shown by a broker to Bank A and is dealt by Bank A. If Bank A wants to increase the amount of the transaction, what is good market practice according to the Model Code:

A) Bank A can call Bank B directly.
B) Bank A should wait 10 minutes before calling Bank B.
C) Bank A cannot increase the amount.
D) Bank A should go back to the broker.