The mirror used by a dentist to check the teeth of a patient is concave (A). Concave mirrors have a reflective surface that curves inward, resembling a portion of the interior of a sphere. This curvature causes light rays to converge at a focal point, producing a magnified image of objects placed within the focal length of the mirror. When a dentist uses a concave mirror, it allows for a larger and clearer view of the teeth and gums, enhancing visibility and aiding in accurate examination and diagnosis. The magnification provided by the concave mirror helps in identifying small details, such as cavities, plaque, or other dental issues that might be difficult to see with the naked eye. This property makes concave mirrors particularly useful in dental practices for thorough and precise inspection of a patient’s oral health.