B is the only one that has only 2 sides of the same length and one that doesn't match the other 2.
A doesn't have any of the lengths being the same
C. is a right triangle, although there can be isosceles right triangles they still need to have only 2 lengths that are the same and in this one, all the values are different
D. This is an equilateral triangle, this has more than 2 lengths that are the same
