The correct answer is C. Thrice.
When the load is increased three times, the torque angle also increases three times. This is because the torque angle is proportional to the load. The torque angle is the angle between the rotor and stator magnetic fields. When the load is increased, the stator magnetic field needs to be stronger in order to produce the same amount of torque. This causes the rotor to lag behind the stator magnetic field by a greater angle.
The other options are incorrect because they do not accurately reflect the relationship between the load and the torque angle. Option A is incorrect because the torque angle does not decrease when the load is increased. Option B is incorrect because the torque angle does not double when the load is increased. Option D is incorrect because the torque angle does not increase six times when the load is increased.