For initial surveys of tunnels, the following activities are involved:1. Marking portal point with concrete pillars on the ground2. Marking tunnel obligatory points on the topographical maps3. Preliminary setting of the tunnel on the topographical Survey of India maps3. Driving lines between the fixed obligatory points.The correct sequence of the activities is :

For initial surveys of tunnels, the following activities are involved:

1.	For initial surveys of tunnels, the following activities are involved: 1. Marking portal point with concrete pillars on the ground 2. Marking tunnel obligatory points on the topographical maps 3. Preliminary setting of the tunnel on the topographical Survey of India maps 3. Driving lines between the fixed obligatory points. The correct sequence of the activities is :
A.	3 2 4 1
B.	1 2 3 4
C.	4 3 1 2
D.	2 4 3 1
Answer» B. 1 2 3 4