Ravi told his friend that his house is $1 \,km$ toward south from the main Post Office. Express the displacement and the distance moved by the friend from the Post Office when he arrives at Ravi's house. Mention the reference point chosen by you.

(N/A) The reference point chosen is the Post Office,which acts as the origin of the motion.
Since the friend travels in a straight line from the Post Office to Ravi's house,the path length is equal to the shortest distance between the two points.
Distance is the total path length covered,which is $1 \,km$.
Displacement is the shortest distance between the initial position (Post Office) and the final position (Ravi's house),which is $1 \,km$ in the southward direction.
Therefore,both the distance and the magnitude of displacement are $1 \,km$.