Final answer:
A projector weighing 429 lb should be mounted on a concrete or brick wall, and possibly on a structural metal wall, for proper support. Wooden walls may require reinforcement to safely support this weight.
Step-by-step explanation:
The question is about which type of surface a projector weighing 429 lb should be mounted to for safety and stability. Due to the significant weight of the projector, it should be mounted on a surface that has sufficient structural support to handle the load. The options provided are concrete, wooden, metal, and brick walls. Generally, a concrete wall or a brick wall is capable of supporting such a weight securely, provided that the correct mounting hardware is used and the installation is performed correctly.
Metal walls can also be suitable if they are structural and of sufficient thickness, but this is less common in typical building construction. Wooden walls might not provide the necessary support unless they are reinforced and the mounting spreads the load across multiple structural members such as studs.