What is the base unit for measuring length in the metric system?

The base unit for measuring length in the metric system is the meter. The metric system is a decimal-based system of measurement that is used internationally and is built around the meter as its fundamental unit for length.

The meter is defined as the distance light travels in a vacuum in 1/299,792,458 seconds, which provides a precise and universal standard. It is a central part of the International System of Units (SI), serving as the starting point for larger and smaller units such as kilometers and centimeters.

In contrast, the other choices provided represent different types of measurements. The liter is the base unit of volume in the metric system, while the gram is the base unit for mass. The yard is a unit of length but is part of the imperial system, primarily used in the United States and a few other countries, making it not applicable in the context of the metric system.