When the price of product a rises, the quantity of product b that is purchased decreases. products a and b are:

They are Complimentary Goods.

Explanation:

Complimentary goods are defined in economics as products that  whose use is related to the use of an associated or paired good.

i.e.: Like Cars and Petroleum

When the price is increase in one product, then the quantity demand for that product decreases. This in tern affects the other related product and the quantity demand of that related product  falls as well.

The goal of any credit card holder should be to C.) AVOID EXCESSIVE CREDIT CARD DEBT.

Credit cards are used for the purpose of convenience. Instead of bringing cash to pay for purchases, credit cards are swiped as payment for said purchases. These cards are short-term loans. Its balance should be paid before due date to avoid paying for interest. Its use should not be abused.