First check whether this could be a right triangle. Using the Pythagorean Theorem, we get:
5^2 + 6^2 = ? = 7^2 This equation is not true, and therefore the triangle is not a right triangle.
The side lengths 5, 6 and 7 are very close to one another, and so the triangle must have essentially similar interior angles, which means that all three angles are acute. Answer D is correct: This is an acute triangle.
