If the Bank of Canada Buys $3 Billion Worth of Japanese

Multiple Choice

If the Bank of Canada buys $3 billion worth of Japanese yen,$4 billion of German marks,and $2 billion of French francs,and sells $5 billion of British pounds,how does this affect the official settlements balance?

A) falls by $4 billion
B) rises by $4 billion
C) rises by $9 billion
D) falls by $5 billion