Final answer:
Lug nuts must be inspected for cracks, distortions, and signs of looseness like rust trails or shiny threads as they are critical for wheel security.
Step-by-step explanation:
The component among the options provided that must be inspected for cracks, distortions, and signs of looseness like rust trails or shiny threads is C. Lug nuts. Lug nuts are crucial in securing the wheel to the vehicle's hub; if they are compromised, it could lead to wheel detachment while driving, posing a severe safety risk. It is important for lug nuts to be properly torqued and in good condition to ensure the vehicle's safety. Checking for visible rust trails may indicate that they have become loose over time, while shiny threads can suggest that they have been moving against another part, both of which are tell-tale signs of potential failure. Therefore, part of regular vehicle maintenance involves inspecting the lug nuts for any signs of wear or damage. Lug nuts are fasteners that secure the wheels to the vehicle. During inspections, it is important to check them for cracks, distortions, and signs of looseness, such as rust trails or shiny threads. This is crucial for ensuring the proper attachment of the wheels to the vehicle, which is essential for safe operation. The other options (A. Engine oil level, B. Brake fluid level, D. Transmission fluid level) pertain to fluid levels and are not typically checked for cracks, distortions, or signs of looseness.