Which unit of measurement should be used for the vertical axis? A. km B. cm C. mm D. dm

The best choice depends on the range and resolution of the data

being graphed. Sadly, we don't know a thing about your data, so

we're in no position to offer guidance on your choice of units. For

all we know, the most reasonable choice might be the nanometer.

On the other hand, it might well be the light-year. We simply have

no information on which to base a recommendation.