**Explanation:**

The maximum spacing of purlins for standard asbestos roofing sheets is determined by several factors, including the weight of the roofing sheets, the structural capacity of the purlins, and the local building codes and regulations. The purpose of the purlins is to provide support and distribute the weight of the roofing sheets evenly across the roof structure.

**Factors Affecting Maximum Spacing of Purlins:**

1. **Weight of Roofing Sheets:** Standard asbestos roofing sheets can vary in weight depending on their thickness and dimensions. Heavier roofing sheets will require closer spacing of purlins to provide adequate support and prevent sagging or damage.

2. **Structural Capacity of Purlins:** The purlins must have sufficient load-bearing capacity to support the weight of the roofing sheets and any additional loads, such as snow or wind. The spacing of the purlins should be determined based on the maximum load that they can safely carry without excessive deflection or failure.

3. **Building Codes and Regulations:** Local building codes and regulations may specify the maximum spacing of purlins for different types of roofing materials. These codes are designed to ensure the structural integrity and safety of the roof and the building as a whole.

**Reason for Option B (1.4 m):**

Based on industry standards and common practices, the maximum spacing of purlins for standard asbestos roofing sheets is typically around 1.4 meters. This spacing provides adequate support for the roofing sheets while maintaining a cost-effective and efficient design.

Option B (1.4 m) is the correct answer because it aligns with the standard practice and provides the necessary support for the roofing sheets without excessive deflection or failure.