Aluminum cable may be concealed in which of the following?

Aluminum cable is versatile in terms of installation and can be concealed in various locations, making the choice "all of these" the correct option. Concealing aluminum cable in conduit is a common practice, as conduit provides protection against physical damage and environmental factors. This method is widely accepted for both indoor and outdoor scenarios, as it ensures proper handling and durability of the cable over time.

Additionally, aluminum cable can be installed within walls, which is often done in residential and commercial buildings to keep electrical systems hidden from view while still providing necessary power supply. This method allows for the efficient routing of cables without exposing them outside the structured framework.

Furthermore, aluminum cable can be buried underground. When installed underground, it may be subject to local electrical codes and regulations, but this option is typically viable for extended runs of electrical wiring, such as those leading from buildings to external structures or utilities. Proper installation techniques and protective measures must be followed to ensure the longevity and safety of the cables laid underground.

The collective acceptance of these installation methods demonstrates the flexibility and applicability of aluminum cables in various settings, reinforcing the reasoning behind selecting "all of these" as the correct answer.