Suppose Last Month 1 British Pound Could Buy US$4

Suppose last month 1 British pound could buy US$4. This month, 2 British pounds is equivalent to US$4. From this, we know that

A) both the U.S. dollar and the British pound appreciated.
B) the U.S. dollar depreciated, and the British pound appreciated.
C) the U.S. dollar appreciated, and the British pound depreciated.
D) both the U.S. dollar and the British pound depreciated.