If two angles are acute and one is acute, then choose a, for example, all three angles are 60 degrees;

If two angles are acute and the other is obtuse, it is an obtuse triangle. For example, 120 degrees and two 30 degrees for b are also correct;

Two angles are acute and one is right, such as right isosceles triangle, which also meets the requirements;

So I can only choose D.

The second choice is C.