Which CSI part number provides information on Reference Standards that contractors or subcontractors must follow?

The correct choice is rooted in the structure of the Construction Specifications Institute (CSI) MasterFormat. The part number that covers Reference Standards is specifically related to general requirements and specifications that apply to all elements of construction, which is part of Division 1.

Division 1 encompasses administrative aspects, including various standards and criteria that contractors and subcontractors are expected to adhere to throughout the construction process. This division sets the foundation for contract documents and guidelines, enabling consistency and quality across projects by outlining the necessary reference standards.

In contrast, the other part numbers relate to different areas of construction. For instance, Division 2 typically covers site work, while Division 3 focuses on concrete, and Division 4 centers on masonry work. Hence, while these sections are crucial for detailing specific types of work and materials, they do not specifically deal with the reference standards that all parties in a construction project must follow.