Which of the following is not one of the three principles from which the metric system is based?

The choices can be found elsewhere and as follows:

a. There is one unit for each measurable quantity.
b. Prefixes are used to signify multiples of each unit.
c. Metric measurements cannot be converted to any other form of measurement.
d. The basic units are related to each other.

I think the correct answer is option C. Metric measurements cannot be converted to any other form of measurement is false. The opposite of the statement is true.