Which of the following is NOT a unit used in the English measurement system?

The correct answer identifies a unit that is not part of the English measurement system. The meter is a fundamental unit of length in the metric system, while the inch, foot, and yard are all established units within the English system of measurement.

Understanding measurement systems is crucial in aviation maintenance, where different systems may be used depending on the aircraft or technical documentation. In this context, the English system is widely used in the United States, involving units of inches, feet, and yards for measuring length. Recognizing that a meter is a metric unit helps reinforce the distinction between these two systems, which is essential for accurate measurements and conversions in aviation practices.