The correct statement that explains the Pythagorean Theorem is:
If a triangle is a right triangle, then the sum of the squares of the legs is equal to the square of the hypotenuse.
This means that for a right triangle with legs of lengths \(a\) and \(b\), and a hypotenuse of length \(c\), the theorem can be expressed mathematically as:
\[ a^2 + b^2 = c^2 \]