A student used a light microscope to view a blood smear on a microscope slide. An eyepiece graticule was used to measure the diameter of a white blood cell on the slide. The student noted that the white blood cell measured $5$ eyepiece graticule units across. Which further piece of information does the student need in order to find the diameter of the white blood cell in micrometres?
- Acalibration of the eyepiece graticule using a stage micrometer only
- Bcalibration of the eyepiece graticule using a stage micrometer and the magnification of the eyepiece lens
- Cthe magnification of the eyepiece lens only
- Dthe magnification of the eyepiece lens and the magnification of the objective lens