What units are used to measure force?

The correct choice for measuring force is the use of Newtons or pounds. The Newton (N) is the standard unit of force in the International System of Units (SI), defined as the amount of force required to accelerate a one-kilogram mass by one meter per second squared. Pounds are commonly used in the Imperial system, with one pound-force approximately equal to 4.448 Newtons.

In the context of physics, it is essential to recognize that force is a vector quantity, which means it has both magnitude and direction. Whether in Newtons, which is used universally in scientific contexts, or pounds, which is prevalent in everyday uses, these units effectively convey the strength of the force being measured.

Other unit types listed in the other options pertain to different physical quantities. Meters and kilograms are units of distance and mass, respectively, while Joules and watts are used to measure energy and power, and liters and grams relate to volume and mass, respectively. Thus, the correct answer highlights the appropriate units specifically designed for quantifying force.