He inadvertently answered somebody else's problem here 
instead of yours.

I'll just do (b) and (d).  You do the other ones.

A line of symmetry is a line where you could place a mirror 
perpendicular to the paper so that what you would see in the 
mirror would be the rest of the figure (the other half that's 
behind the mirror.)

The green lines are the lines of symmetry:

(b) 

(d)



Edwin