A relay that uses transistors to drive the relay coil
A device that uses semiconductors to implement the functions of an electromechanical relay✓Correct answer
A mechanical relay that latches in the on or off state each time it is pulsed
A semiconductor switch that uses a monostable multivibrator circuit
Explanation
A solid-state relay performs the job of an electromechanical relay — switching a load under control of a separate low-power input, usually with optical isolation between the two — but does it with semiconductors and no moving contacts. A transistor driving a coil is still an electromechanical relay, and latching relays and multivibrator circuits are different devices.