4. If the three vertices of a right-angled triangle are all taken from the vertices of a certain regular dodecagon, then the number of such right-angled triangles is $(\quad)$.
(A) 36
(B) 60
(C) 96
(D) 120
4. B.

Considering on the circumcircle $\odot O$ of this dodecagon, any triangle formed by any three vertices of the dodecagon has $\odot O$ as its circumcircle. If it is a right triangle, then one of its sides must be the diameter of $\odot O$. Among the diagonals of the regular dodecagon, there are 6 diameters. For each pair of endpoints $A, B$ of a diameter, any point $C$ among the remaining 10 points can form a right triangle with $A, B$ with $AB$ as the hypotenuse, i.e., each diameter generates 10 right triangles, resulting in a total of 60 right triangles.