Explanation:
To understand the given problem, we need to have a clear understanding of circle bearings and reduced bearings.

Circle Bearing:
Circle bearing is a method of expressing direction or azimuth in terms of the angle formed between a reference direction (usually North) and the line of interest, measured clockwise from the reference direction. Circle bearings are expressed in degrees, minutes, and seconds.

Reduced Bearing:
Reduced bearing is a simplified form of circle bearing, where the angle is reduced to a value between 0 and 90 degrees. It is expressed using cardinal directions (North, South, East, West) along with the angle in degrees.

Given Information:
- Whole circle bearing of the line is 1200.
- We need to find the reduced bearing of the line.

Steps to Find the Reduced Bearing:

Step 1:
Understand the given whole circle bearing and its components.
- The whole circle bearing is 1200, which means the line is inclined at an angle of 1200 degrees clockwise from the reference direction (usually North).

Step 2:
Convert the whole circle bearing to a reduced bearing.
- Since the reduced bearing is expressed in cardinal directions, we need to determine the quadrant in which the line lies.

Step 3:
Determine the quadrant of the line.
- In this case, the line is inclined 1200 degrees clockwise, which is equivalent to 1200 - 360 = 840 degrees counterclockwise.
- Since 840 degrees lies in the third quadrant (270-360 degrees), the line is in the southwest direction.

Step 4:
Express the reduced bearing using cardinal directions.
- The reduced bearing is expressed as an angle between 0 and 90 degrees in the southwest direction.
- Since the line lies in the southwest direction, the reduced bearing is S600E.

Therefore, the correct answer is option 'B' - S600E.