In a geometry class, the students were asked to prove the theory below by contradiction. Theorem: A triangle has at the most one obtuse angle.

Heather begins the proof with an assumption. Which statement will she most likely use as an assumption.

1. Let two angles of a triangle be obtuse.
   
2. Let each angle of a triangle be acute.
   
3. Let only one angle of a triangle be obtuse.
   
4. Let two angles of a triangle be right.