Practical Geometry Symmetry & Visualising Solid Shapes

Which of the following sets of triangles could be the lengths of the
sides of a right-angled triangle:
(a) 3 cm, 4 cm, 6 cm (b) 9 cm, 16 cm, 26 cm
(c) 1.5 cm, 3.6 cm, 3.9 cm (d) 7 cm, 24 cm, 26 cm