How many base units are in one kilogram?

One kilogram is defined as 1,000 grams, which correspondingly translates to 1,000 base units in the metric system, where the base unit for mass is the gram. The metric system operates on a decimal system that is based on powers of ten, meaning that each step up or down takes you to a multiple or fraction of ten.

In this case, when considering the kilogram as a base unit related to grams, it highlights the direct relationship between them: 1 kilogram equals 1,000 grams. This straightforward conversion solidifies the understanding that in terms of base units, one kilogram is indeed comprised of 1,000 base units. Therefore, in this context, the correct answer correctly represents the conversion metric in the International System of Units (SI).