The Following Are All Procedures to Measure the Field Diameter

The following are all procedures to measure the field diameter EXCEPT which statement?

A) Position the slide so that a vertical line on the paper lines up with the edge of the field.
B) Position the slide so that the horizontal line on the paper is on the top of the field.
C) Count the number of millimeters across the field to measure the field diameter.
D) Use your low-power measured field diameter to calculate the field diameter for high power.