In some ways this can be considered to be a trick question. Mezzotint is a printing method by which the plate is created using small dots. This is not the same method that is used to create traditional halftones, cross-hatch or stippling. This form of printing is rather uncommon in today’s commercial print markets.
Depending on the way the plate is burnished, some areas will attract the black ink while others will not. The places in the plate that do not attract black ink will remain white. If an area of the plate is smoothed in a certain way, the small amount of black ink will be transferred to the print in a minute amount, making it appear to be gray. In essence, only black ink is used but as with many halftone methods, there are appearances of gray. To the naked eye, there are most definitely shades of gray.