Voltage is sometimes referred to as EMF, or Electromotive…?

The correct answer is: Electromotive Force.

Electromotive force (EMF) is the electrical potential energy per unit charge that is available for conversion into other forms of energy, such as electrical work. It is measured in volts (V).

The other options are incorrect because:

• Field is a region of space in which a physical quantity, such as a force, has a constant value.
• Factor is a number or quantity that is multiplied by another to produce a result.
• Flash is a sudden burst of light.
• Force is an interaction between two objects that causes a change in their motion.