Answer:
15 gallons could be from a discrete set of whole numbers only, however a gas tank can be any size such as 15.6 or 14.3 and is therefore continuous since there are infinite options.
Explanation:
Discrete means a restricted set of numbers can be the domain such as only whole numbers.
Continuous means the domain is infinite and not countable and can been seen when decimals or fractions are a part of the domain.