Final answer:
To create a watertight connection between the roof and roof drains, a specialized roofing membrane is used to prevent water leakage and damage.
Step-by-step explanation:
The connection between the roof and roof drains that pass through the roof and into the interior of the building is critical for preventing water damage.
To ensure this connection is watertight, a roofing membrane is typically used due to its effectiveness in sealing and protecting against water penetration. The other options listed, like roofing cement, roofing nails, and roofing shingles, may be part of the overall roofing installation, but for the specific purpose of creating a watertight seal at the point where roof drains are integrated, a specialized roofing membrane is the best choice. These membranes are designed to conform to the shape of the roof and its features, creating a continuous barrier that prevents water leakage.