Final answer:
The term/unit used to express the resolution of a diagnostic image is angular separation. In biology, resolution refers to the ability of a lens to produce sharp images of two closely spaced point objects. The smaller the distance between the objects that can still be seen as distinct, the greater the resolution.
Step-by-step explanation:
The term/unit used to express the resolution of a diagnostic image is angular separation. In biology, when using a microscope, resolution refers to the ability of a lens to produce sharp images of two closely spaced point objects. The smaller the distance between the objects that can still be seen as distinct, the greater the resolution.