On October 20 of last year, Amos retired from the Ahlgren Partnership, a calendar-year partnership. Amos continued to receive retirement payments until July 30 of the current year, when his entire partnership interest was liquidated. For tax purposes, when did Amos cease to be regarded as a partner

A. December 31 of last year.

B. October 20 of last year.

C. December 31 of the current year.

D. July 30 of the current year.