2. Among all the interior angles of a convex octagon, the number of obtuse angles is at least ( ) .
(A) 3
(B) 5
(C) 7
(D) 8
2. (B).

Since the exterior angles of a convex polygon can have at most 3 obtuse angles, its interior angles can have at most 3 acute angles. Therefore, in a convex octagon, there are at least 5 obtuse angles among the interior angles.