Final answer:
Water-resistant drywall should be used when installing bathroom tiles to prevent water damage and mold growth. Option C is correct.
Step-by-step explanation:
The question asks which installation should involve a backing of water-resistant drywall. The correct answer is c. Bathroom tiles. This type of drywall, often referred to as 'green board' because of its green color, is specifically designed for use in areas with high moisture levels such as bathrooms.
Using water-resistant drywall is critical in these areas to prevent water damage and the growth of mold and mildew, which are health concerns and can lead to significant repair costs if the wrong materials are used.
A backing of water-resistant drywall should be used when installing bathroom tiles. This is because bathroom tiles are constantly exposed to moisture and water, and regular drywall can get damaged easily. Water-resistant drywall is designed to withstand moisture and prevent any damage to the tiles or the underlying structure.