Correct option is B
Solution:
Here as shown in the image man started from point A and reaches at the point D
We draw a line from A parallel to BC to meet CD at E .
Here AED forms a right angles triangle whose hypotenuse is AD
Hence (AD)² = (ED)² +(AE)²
(AD)² = (12)² +(9)²
AD = 15km
So we can clearly see the man is 15km from his starting point