Money that is collecting interest in a bank account doubles in value every 10 years.
When the account was opened, it had 16, or 2 to the power of 4, dollars in it. After 50 years, the account balance has doubled 5 times, increasing by a factor of 2 to the 5th power.
It now has a balance of 2 to the 4th power x 2 to the 5th power. Expressed as a power, how much money, in dollars, is in the account after 50 years?

A. 4 to the power of 9
B. 2 to the power of 20
C. 2 to the power of 9
D. 2 to the power of 5