2015 audit fees

An audited entity company has not paid its 2015 audit fees. According to the AICPA Code of Professional Conduct, for the auditor to be considered independent with respect to the 2016 audit, the 2015 audit fees must be paid before the
a. 2015 report is issued.
b. 2016 fieldwork is started.
c. 2016 report is issued.
d. 2017 fieldwork is started.