The correct option is A Standardized units vary from person to person.
If the measurement units are not standardized, there will be no accuracy or uniformity in the measurements. Standardized units are globally accepted so these units can be used anywhere in the world. But if we use a unit which is not standardized then these might not get accepted at many places.
Also, since everyone accepts the standardized units, it becomes convenient to measure anything, anywhere and also the standardized measuring instruments are easily available everywhere.