Which method is used to visually check equipment's condition without tools?

The correct choice involves a combination of visual and auditory inspection, which allows for a comprehensive assessment of equipment condition without the need for specialized tools. This method is effective because it utilizes the senses to identify any visible signs of wear, damage, or abnormal conditions, as well as listening for unusual sounds that may indicate operational issues.

Visual inspection alone can reveal physical defects, leaks, or other surface-level problems, while auditory inspection helps in recognizing abnormalities in sounds associated with the equipment's operation, such as vibrations, rattles, or humming noises that could signify malfunction. The combination of both methods enhances the ability to detect issues early, ensuring that preventative measures can be implemented before more significant problems arise.

Other methods mentioned do not fit as well with the requirement of not using tools. Auditory detection focuses solely on sound, which may not provide a full picture if visual assessment is necessary. Manual inspection often implies a hands-on approach that might involve touching or physically interacting with the equipment, which could be interpreted as using tools or instruments. Remote inspection typically involves technology or devices to observe equipment from a distance, which is not what is being asked in this scenario.