If the chain line which runs along the N-S direction is horizontal and the ground in the E-W direction is sloping:

🌍 Visualizing the Scenario

Let's break down the situation:

• Chain Line (N-S): This is your main survey line. The question states this line is perfectly horizontal. Imagine walking along a level path on the side of a hill.
• Ground Slope (E-W): This is the "cross-slope." The ground is sloping up or down perpendicular to your path. To your left (West) and right (East), the ground is not level with your chain line.

The core task is to measure offsets, which are short, perpendicular distances from the chain line to features of interest (like a tree or a building corner).

📏 The Fundamental Rule of Offsets

The most important principle in setting offsets is that they must always represent the true horizontal distance from the chain line to the object. The measurement must be taken both horizontally and at a perfect 90° angle to the chain line.

If you were to measure along the sloping ground surface, you would be measuring a longer, incorrect slope distance instead of the true horizontal offset.

🛠️ Correct Field Procedure on Sloping Ground

Surveyors have a standard method to handle this exact situation, which works whether the ground slopes up or down, to the east or to the west.

1. The surveyor holds the zero end of the tape at the object.
2. The assistant holds the tape at the chain line, ensuring it is pulled taut and, most importantly, perfectly horizontal. A hand level can be used to ensure this.
3. The assistant then uses a plumb bob to transfer the correct point on the horizontal tape vertically down to the chain line. The reading is then taken.

This procedure guarantees that the measured distance is the true horizontal offset. Since this method is independent of the direction of the slope, it can be applied correctly on both the east and west sides of the chain line.

Therefore, it is entirely possible to set offsets correctly on both sides, making option (D) the correct answer.