Which of the following is the base unit of length in the metric system?

• A. meter
• B. kilometer
• C. centimeter
• D. millimeter

Answer: (A)

Verified step by step guidance

1. Understand that the metric system is based on a set of base units for different physical quantities, such as length, mass, and time.
2. Recall that the base unit of length in the metric system is the fundamental unit from which other units of length are derived by using prefixes.
3. Identify the options given: meter, kilometer, centimeter, and millimeter. Notice that kilometer, centimeter, and millimeter are all multiples or fractions of the meter, indicated by their prefixes (kilo-, centi-, milli-).
4. Recognize that the base unit itself does not have a prefix and serves as the standard unit for length measurement in the metric system.
5. Conclude that the base unit of length in the metric system is the meter, and the other options are derived units based on it.