If the European Central Bank Desires to Weaken the Euro

If the European Central Bank desires to weaken the euro without affecting the euro money supply, it should:

A) exchange euros for foreign currencies, and sell some of its existing Treasury security holdings for euros.
B) exchange foreign currencies for euros, and sell some of its existing Treasury security holdings for euros.
C) exchange euros for foreign currencies, and buy existing Treasury securities with euros.
D) exchange foreign currencies for euros, and buy existing Treasury securities with euros.