To convert milliliters to liters, you can use the conversion ratio of 1 liter = 1,000 milliliters.
Given that the cylinder holds 6,750 milliliters, the conversion to liters can be calculated as follows:
\[ \text{Liters} = \frac{\text{Milliliters}}{1,000} = \frac{6,750}{1,000} = 6.75 \]
So, the cylinder holds 6.75 liters.
The correct response is 6.75.