None, since there is no such thing as rational symmetry.
triangle
is a square a rational symmetry? is a square a rational symmetry?
One line of symmetry
It has 1 line of symmetry
none
There are infinitely many lines of symmetry. Every line can be a line of symmetry for a suitable shape.
It has 1 vertical line of symmetry
A line has only 1 line of symmetry that i know of.
A cardioid has 1 line of symmetry.
A line has 180 degrees rotational symmetry.
Assuming the question is about ROTATIONAL symmetry rather than rational symmetry, the answer is none.
The line of symmetry is the reflection of an object. The Letter F does not have a line of symmetry.