Final answer:
The ounce is not an SI base unit; it is part of the American system of measurement. The SI base units are used in scientific measurements and include the second, meter, and kilogram.
Step-by-step explanation:
The ounce is NOT a base unit of the International System of Units (SI). The base SI units include the second (s) for time, the meter (m) for length, and the kilogram (kg) for mass. The unit ounce is part of the American system of measurement and is used for weighing mass, where it represents 1/16 of a pound. The meter is the SI base unit for length, the kilogram is the base unit for mass, and the second is the base unit for time.
The other options listed - second, mole, and meter - are indeed part of the seven SI base units, which are used worldwide by scientists and clearly define quantities without reference to other units. The SI system is a metric system, and it uses prefixes like kilo-, milli-, nano-, and centi- to scale the base units up or down. For example, a kilometer (km) is 1,000 meters, a milligram (mg) is 0.001 grams, a nanosecond (ns) is 0.000000001 seconds, and a centiliter (cl) is 0.01 liters. Each of these is measured against the base unit in the metric system.