If Annie and Andy (Each a 30% Shareholder in an Calendar

If Annie and Andy (each a 30% shareholder in an calendar year S corporation) file a revocation statement on February 10,2017 to terminate their S corporation's S election,what is the effective date of the S corporation termination (assuming they do not specify one) ?

A) January 1, 2017.
B) February 10, 2017.
C) January 1, 2018.
D) February 10, 2018.
E) None of the choices are correct.