Two planes intersect in a line that contain all common points of these two planes.
1. Plane named ABFE contains points A, B, F and E.
2. Plane named BFCD contains points B, F, C and D.
As you can see points B and F are common points for these two planes, then the line of intersection is BF and its notation is [tex]\overleftrightarrow{BF}.[/tex]
Note that notation [tex]\overline{BF}[/tex] stays for segments and notation [tex]\overrightarrow{BF}[/tex] stays for rays.
Answer: correct choice is A.
