Which of the following is NOT a material used for covering a pitched roof?

The selection of plastic sheets as the answer reflects a nuanced understanding of roofing materials and their typical applications. Pitched roofs are traditionally covered with materials that provide durability, weather resistance, and structural integrity. Cement tiles, mineral fiber, and clay tiles are all conventional roofing materials known for their effectiveness on pitched roofs.

Cement tiles are valued for their strength and longevity, making them suitable for steep slopes. Clay tiles offer excellent durability and aesthetic appeal, commonly found in residential architecture. Mineral fiber, while not as common as the first two, can be used in certain roofing applications, especially for certain types of insulation or as part of a composite roofing system.

Plastic sheets, on the other hand, are generally not employed as a primary covering for pitched roofs. They may be used in specific circumstances such as temporary coverings or underlayment but lack the necessary durability and weather-resistant properties typically required for an effective pitched roof covering. Therefore, the identification of plastic sheets as not being a conventional roofing material aligns with established practices in carpentry and roofing applications.