Final answer:
Without specific information on the image receptor's properties like pixel size, it is not possible to accurately determine its spatial resolution in line pairs per millimeter.
Step-by-step explanation:
The spatial resolution of an imaging system describes its ability to distinguish small details in an image, often measured in line pairs per millimeter (lp/mm). However, the resolution depends on various factors including the pixel size of the image sensor, the quality of the lens, and the image processing algorithms. The specific information about an image receptor's spatial resolution can typically be found in its technical specifications, which are provided by the manufacturer. As the provided reference information does not directly pertain to the spatial resolution of a 24 cm x 30 cm image receptor, and without knowing the exact properties of the receptor such as pixel size or sensor design, it is not possible to accurately answer whether the resolution is 2, 3, 4, or 5 ip/mm.