Which of the following statements is/are correct?

A. A triangle can have all angles less than 60°.

B. A triangle can have one obtuse angle.

C. A triangle can have two right angles.

D. A triangle can have two acute angles.

The correct option is B and D.

Let us analyze each statement individually based on the properties of a triangle:

Statement A: A triangle can have all angles less than 60°.
The sum of all three interior angles in any triangle must always equal 180°. If all three angles were less than 60°, their sum would be less than:

$60°+60°+60°=180°$

Since the sum must equal 180°, it is impossible for all three angles to be strictly less than 60°. Therefore, Statement A is incorrect.

Statement B: A triangle can have one obtuse angle.
An obtuse angle is an angle greater than 90°. A triangle can have one obtuse angle along with two acute angles (for example, interior angles measuring 100°, 40°, and 40° sum up to 180°). Such a triangle is known as an obtuse-angled triangle. Therefore, Statement B is correct.

Statement C: A triangle can have two right angles.
A right angle measures 90°. If a triangle had two right angles, the sum of just those two angles would be:

$90°+90°=180°$

This leaves 0° for the third angle, which cannot form a valid triangle. Therefore, Statement C is incorrect.

Statement D: A triangle can have two acute angles.
An acute angle measures less than 90°. Every triangle contains at least two acute angles (for example, an acute triangle with 60°, 60°, 60°, a right triangle with 90°, 45°, 45°, or an obtuse triangle with 100°, 40°, 40°). Therefore, Statement D is correct.

Hence, the correct statements are B and D.