Which of the following units is part of the conventional (U.S. or English) measurement system?

The ounce is part of the conventional U.S. measurement system, commonly used for both weight and volume. In the context of measuring weight, the ounce is often utilized in everyday life, especially in cooking and food labeling, where smaller quantities are frequently measured. The U.S. customary units include measurements such as ounces, pounds, gallons, and inches, which differ from the metric system that uses units like meters, grams, and liters.

In contrast, the meter and kilogram are units from the metric system, which is utilized globally and is based on decimal multiples. The milligram, being another metric unit, is part of this same system and is typically used for measuring very small weights. Understanding the distinction between the two systems is crucial in various fields, such as science, engineering, and daily activities, as both systems have their specific applications and contexts.