4. (10 points) Among the interior angles of seven triangles, there are two right angles and three obtuse angles. Therefore, there are ( ) acute triangles.
A. 1
B. 2
C. 3
D. 4
【Analysis】Since a triangle can have at most one right angle or one obtuse angle, according to the problem: there are 2 right-angled triangles, 3 obtuse-angled triangles. As there are a total of 7 triangles, using $7-3-2$ can determine the number of acute-angled triangles.

【Solution】Solution: $7-2-3=2$,
Therefore, there are 2 acute-angled triangles.
So the answer is: $B$.