The letter 'S' does not have a line of symmetry as none of the lines divide it into two halves which are mirror images of each other.

The alphabet 'X' has two lines of symmetry.

and 'A' 'B' and 'U' has only one line of symmetry as shown below.
 

Answer: Option A. ->

Line of symmetry is a line with respect to which the two halves are mirror images of each other. We see that in the correct option, the line acts as a line of symmetry as the halves are mirror images of each other with respect to that line.

Asymmetrical figures are those which do not have a line of symmetry and hence are not symmetrical.  As in the above figure, there is no line of symmetry, the given figure is asymmetrical.

A circle has more than two lines of symmetry.

An isosceles trapezium has only one line of symmetry.

An isosceles triangle has only one line of symmetry.
A parallelogram has only one lines of symmetry.

Regular octagon has eight lines of symmetry as shown below.

Except 'T' all the other options would look different after reflection. For example:

But 'T' will look the same on reflection in a vertical mirror as shown below.

The image formed in a plane mirror is of the same length of the object. So, the image of the line would remain a line and there would be no change in its length.
$\therefore$ refelction is a line of length 10cm.

The line of symmetry is an imaginary line, when we fold the figure along the dotted line of symmetry, the figure is exactly divided into two identical halves.

Each option: 1 Mark
(a) Yes, L is the line of symmetry as it divides the pizza into two identical parts.
(b)  We can have only one line of symmetry for this figure.