Answered

When you buy a U.S. government savings bond, you're doing so under the power given to Congress to A. regulate commerce. B. print and coin money. C. levy taxes. D. borrow money.



Answer :

When you buy a U.S. government savings bond, you're doing so under the power given to Congress to borrow money
Answer; D
Borrow money;
When you buy a U.S. government savings bond, you're doing so under the power given to Congress to borrow money

Explanation; 
Borrowing money in this case, entails lending money to an entity when you buy a  bond from it. You give the entity the power to borrow. 
The U.S. government has the power to regulate commerce, levy taxes, print and coin money regardless of bond issuance. Buying bonds does not increase the power.