What device converts electrical energy into a linear force?

A solenoid is the correct choice as it is a device specifically designed to convert electrical energy into linear force. It operates by generating a magnetic field when an electric current flows through its coil. This magnetic field creates linear motion of a movable iron core (or plunger) within the solenoid, resulting in mechanical movement.

In contrast, while a motor also converts electrical energy into mechanical energy, it typically produces rotational force rather than linear force. A transformer is designed to transfer electrical energy between circuits through electromagnetic induction but does not have a direct output of mechanical force. A generator, on the other hand, converts mechanical energy into electrical energy, which is the opposite of what is being asked in the question. Therefore, the solenoid is uniquely suited for producing a linear force from electrical energy.