For a synchronous motor, the nature of speed-torque characteristic if torque is on Y axis and speed is on X axis is a:

Correct option is A

For a synchronous motor, the speed-torque characteristic shows the following behavior:
· Speed-Torque Characteristic: In synchronous motors, the speed remains constant at synchronous speed regardless of the load torque (within limits). Therefore, the characteristic curve for torque versus speed is a vertical line.
· Torque (Y-axis) vs. Speed (X-axis): Since the synchronous motor operates at a constant speed, as you increase the load (torque), the motor maintains its synchronous speed until it reaches its maximum torque capability. Beyond this point, it will drop out of synchronization.