Answer:
B) 1
Step-by-step explanation:
When reading the problem it tries to trip you up with the black dot. A line of symetery marks where you can cut the shape in half and have both parts equal. With the black dot a part of the shape there is only one way for a line of symetery to work as it can only be split in half that one way. No other corners have a black dot so there is no other way to split it where it would be symetrical.
