A Right triangle is a triangle that has an angle whose measure is 90 degrees.
The Pythagorean Theorem states that:
Where "a" is the hypotenuse (the longest side of the Right triangle) and "b" and "c" are the legs of the triangle.
Knowing the above, you can check each set:
Set A
Notice that the longest side is 8. Then:
This set couldn't form a Right triangle.
Set B
The longest side is 15. Then:
This set could form a Right triangle.
Set C
Knowing that the longest side is 20, you get:
This set couldn't form a Right triangle.
Set D
The longest side is 30. Then:
This set couldn't form a Right triangle.
The answer is: Option B.