What is a Synchronous condenser?

Correct option is D

​$$\text{A synchronous condenser is a synchronous motor running without any mechanical load and operated at over-excitation.} \\[10pt]\bullet \ \text{When a synchronous motor is over-excited, it draws a leading current from the supply.} \\[4pt]\bullet \ \text{This leading current provides reactive power (kVAr) to the system.} \\[4pt]\bullet \ \text{As a result, it improves the power factor and helps in voltage regulation of the power system.} \\[10pt]\text{Thus, a synchronous condenser behaves like a variable capacitor, but with better control and higher ratings.}$$​​