When was ASC $606-10$ first effective for a private company with a calendar year$-$end? Hint: You will need to review ASU $2020-05$ to find this information, including the Codification paragraph that included this guidance. Given that the transition to ASC $606-10$ has been completed, this paragraph is no longer available in the Codification.

Select one:

a$.$

For annual reporting periods beginning after Dec. $15,2017,$ including interim reporting periods within that reporting period.

b$.$

For annual reporting periods ending after Dec. $15,2017,$ including interim reporting periods within that reporting period.

c$.$

For annual reporting periods ending after Dec. $15,2019,$ including interim reporting periods within that reporting period.

d$.$

For annual reporting periods beginning after Dec. $15,2019$ and interim periods beginning after Dec. $15,2020.$