Correct Answer: (b)13 m

Explanation:

Let the poles be and CD

AB = 6 m

CD = 11 m

Let AC be 12 m

Draw a perpendicular from CD, meeting CD at E.

BE = 12 m

Applying Pythagoras theorem in right-angled triangle BED,

????????² = ????????² + ????????²

=> 12² + 5²

=> 144 + 25

=> 169

BD = 13 m