In microscopy, what does the term 'resolution' refer to?

Resolution in microscopy is a critical concept that refers to the ability to distinguish two points as separate entities within an image. It primarily relates to the clarity and sharpness of the image produced by the microscope. High resolution means that fine details can be observed clearly, allowing for a better understanding of the structure and features of the specimen being examined. This is essential for scientists and students studying cells and tissues, as it enables them to identify and analyze distinct cellular components.

The other options, while related to the experience of microscopy, do not accurately define resolution. For instance, the size of the specimen influences how it fits in the field of view but does not affect how clearly the details can be seen. Similarly, brightness is about the amount of light in an image rather than its sharpness. Finally, the distance from the lens affects focus rather than resolution itself, as proper focusing is necessary to achieve clear images, but it does not define the resolving power of the microscope.