A. Shunt capacitor
B. Shunt Reactor
C. Series capacitor
D. Series Reactor
Answer: B. Shunt Reactor
Explanation:
The synchronous phase modifier is a synchronous motor that is not connected to any load.
When a synchronous motor is under-excited its works as an inductor or shunt Reactor.
The shunt reactors are used across capacitive loads or lightly loaded lines to absorb leading vars to control the voltage across the load to within certain desirable limits.