To find the starting point of Nandalal's journey we have to move in the reverse direction i.e.
He turned left and covered a distance of 20 km. It means he is walking in East direction and take left to move in North direction
After walking 12 km, Nandalal turned right and covered a distance of 4 km. It means he is waking in the South direction and take a right turn to move in East direction.
So, Nandlal starts his journey from the south direction.
The below-given diagram shows Nandalal's journey:
Point A shows the starting point and point B shows the endpoint. Thus, the direction of his starting point with respect to his ending point is south-west.
Hence, "South-west" is the correct answer.