Step 1: Understanding the Concept:
Tractor tyres can be of radial-ply or bias-ply construction.
Each type has specific advantages.
Step 2: Key Formula or Approach:
No specific formula.
Need to know the characteristics of each tyre type.
Step 3: Detailed Explanation:
Radial-ply tyres have flexible sidewalls.
They improve traction and tractive efficiency.
They are suitable for soft soil due to better flotation.
Bias-ply tyres have stiff sidewalls.
They are suitable for hard surfaces and heavy loads.
They work well on highways.
Bias-ply tyres are not suitable for soft soil.
Thus, A, B, and C are correct for radial-ply tyres.
Step 4: Final Answer:
Radial-ply tyres improve coefficient of traction, tractive efficiency, and are advantageous for soft soil.
Hence, the correct option is (A).