The digit having only one line of symmetry is _____
A. 0
B. 3
C. 5
D. 9

Hint: Here we use the concept of symmetry which states that line of symmetry divides a figure into identical half so when we map the exact half we get the complete figure. We check for each of the given options by drawing a number of possible lines of symmetry for each number.

Complete step-by-step solution:
We know that line of symmetry divides a figure into identical half so when we map the exact half we get the complete figure.
Let us try drawing the maximum number of possible lines of symmetry for each of the given options.
OPTION A:
We are given the number ‘0’

We can see from the figure, there are at most two lines of symmetry for the digit ‘0’.
OPTION B:
We are given the number ‘3’

We can see from the figure, there is only one line of symmetry for the digit ‘3’.
OPTION C:
We are given the number ‘5’

We can see from the figure, there is no line of symmetry for the digit ‘5’.
OPTION D:
We are given the number ‘9’

We can see from the figure, there is no line of symmetry for the digit ‘9’.
So, the only digit that has one line of symmetry is ‘3’

\[\therefore \]Option B is correct.

Note: Line of symmetry is always a straight line. The lines of symmetry can be horizontal, vertical or slant but can never be curved.