Answer:
D
Step-by-step explanation:
Using the converse of Pythagoras' identity.
If the square of the longest side is equal to the sum of the squares on the other two sides then the triangle is right.
longest side = 12 and 12² = 144
5² + 8² = 25 + 64 = 89
Since 5² + 8² ≠ 12² , then triangle is not right → D
