2. Among the triangles formed by any 4 points on a plane, the maximum number of obtuse triangles is ( ).
(A) 5
(B) 2
(C) 4
(D) 3
【Answer】 $\mathrm{C}$
【Question Type】Maximum value, Construction
【Analysis】4 points, the maximum number of triangles that can be constructed is $C_{4}^{3}=4$. As shown in the figure, all four triangles in the diagram are obtuse triangles.