Which of the following correctly describes the sum of two rational numbers?

"The sum of two rational numbers is rational."  

By definition, a rational number can be expressed as a fraction with integer values in the numerator and denominator (denominator not zero). So, adding two rationals is the same as adding two such fractions, which will result in another fraction of this same form since integers are closed under addition and multiplication. Thus, adding two rational numbers produces another rational number.

No, they couldn't.

Step-by-step explanation:

The rule for triangle side lengths is that any two lengths added up must equal more than the last one. for it to be able to form a triangle.

Ex: 1 + 2 is not greater than four, so it isn't a triangle.

With the numbers 4, 5, and 6 however, 4 + 5 is greater than 6, 6 + 5 is greater than 4, and 4 + 6 is greater than 5. That triangle would work.