A man walks 3 km west, then turns north and walks 4 km. How far is he from the starting point? ​​

Given: 

A man walks 3 km west, then turns north and walks 4 km.

Distance = $$\sqrt{ (3^2 + 4^2)}$$

= $$\sqrt {(9 + 16)}$$

= $$\sqrt {25}$$

= 5km

He far 5km from the starting point.

Thus, correct option is (d).