Which of the following is true regarding rational numbers?

The statement that all integers are rational numbers is indeed correct because rational numbers are defined as any number that can be expressed as the quotient of two integers, where the denominator is not zero. Since any integer can be represented as itself divided by one (for example, the integer 5 can be expressed as 5/1), it qualifies as a rational number. Thus, every integer indeed fits the broad category of rational numbers, showcasing the relationship between the two sets.

The other options do not hold true. The first option falsely suggests that every rational number is an integer, which is not the case since rational numbers can also include fractions (e.g., 1/2, 3/4) that are not whole numbers. The third option incorrectly states that no rational number can be expressed as a fraction; in fact, that is the defining characteristic of rational numbers. Lastly, the fourth option is misleading because all rational numbers can be expressed as either terminating or repeating decimals, not as entirely non-decimal forms. Therefore, recognizing that all integers fall under the category of rational numbers reinforces the understanding of their relationship within the number system.