which side lengths form a right triangle? A, B or C?

Answer:
B
Step-by-step explanation:
B.
Side lengths that for a right triangle will always follow the following rule:
a^2+b^2=c^2
Where a and b are the legs of the triangle, and c is the hypotenuse.
So to see this we can put it into that equation.
1.5^2+2^2=2.5^2
2.25+2=6.25
6.25=6.25
Therefore, these side lengths do form a right triangle.