Which of the following best describes a medical device?

A medical device is defined as an apparatus designed specifically for medical purposes, which includes diagnosing, preventing, monitoring, or treating health conditions. This definition aligns closely with the second option, as it accurately captures the essence of medical devices as tools essential for health-related functions.

Medical devices encompass a vast range of products, from simple tools like tongue depressors to complex machinery like MRI machines. Their primary aim is to provide healthcare professionals with the means to support patient health effectively.

The other options do not accurately encapsulate the broader scope of medical devices. For instance, the first option refers to items that necessitate chemical action, which could describe drugs but does not define medical devices comprehensively. The third option is too narrow, as it focuses solely on affecting mental states, which is not representative of all medical devices. The fourth option mentions a surgical robot, which is indeed a type of medical device; however, it represents a specific category within the larger context of medical devices and does not account for the full spectrum of devices used in healthcare. Thus, the second option is the most comprehensive and accurate description of what constitutes a medical device.