The number of lines of symmetry in a 30° - 60°- 90° set square is

We can see that in the given set square all the 3 angles are different, which means that all its sides will also be different so the given set square is of the shape of the scalene triangle.

And we know that the scalene triangle does not have any lines of symmetry, so we can say that, the 30^o - 60^o - 90^o set square has 0 lines of symmetry.

∴ the correct option is A.