The angles of rotations (rotational symmetry) of an equilateral triangle are:

Given: 

Angles are given where the equilateral triangle rotate.

Concept used: Rotational symmetry is the symmetry when it looks the same after some rotation by a partial turn.

In a regular polygon divide 360º by the number of sides to get the smallest angle of rotation.

Calculation: In the given figure is equilateral triangle which is regular polygon. 

Here, the number of sides = 3 

Smallest angle of rotation = 360º / 3 

⇒ 120º

If we rotate the polygon the angle at 240º, after that the polygon looks same.

And also if rotate at 360º, it mean complete rotation, also it looks same. 

∴ The angles of rotation are 120º, 240º, 360º.

∴ Option 3 is correct.