How many milligrams are in 1 gram?

One gram is equivalent to 1000 milligrams due to the metric system's base-10 structure. In this system, the prefix 'milli-' signifies one thousandth of a unit. Thus, when converting grams to milligrams, you multiply the number of grams by 1000. Therefore, since 1 gram is equal to 1000 milligrams, the correct choice accurately reflects this conversion. Understanding these conversions is essential in various fields, including healthcare, where precise measurements of medication dosages are crucial.