Oehlers, CPA, is a staff auditor participating in the engagement of Capital Trust, Inc. Which of the following circumstances impairs Oehlers' independence?

A$.$ During the period of professional engagement, Capital Trust and Oehlers discussed business over lunch at a first $-$ class restaurant.

B$.$ Oehlers' friend, an employee of another local accounting firm, prepares the tax return of Capital Trust's CEO.

C$.$ Oehlers' and Capital Trust's $401$ K plans own stock with the same corporation.

D$.$ Oehlers' sister is an internal auditor employed by Capital Trust