In the given circuit, if the resistance R is varied from

1. phase remains constant.
2. phase varies from 0 to ± 90°
3. magnitude is constant and phase varies from 0 to 180°
4. phase of the circuit is given by 2 tan^-1 1
  ωCR

phase of the circuit is given by 2 tan^-1	1
	ωCR