. REGARD/ YOUR APPLICATION/ REGRET/ INFORM/ VACANCY/ ALREADY/ FILL....

10/. regard/ your application/ regret/ inform/ vacancy/ already/ fill.

A. As regards your application, I regret to inform you that the vacancy has already been filled.

B. As regards your application, I regret informing you that the vacancy has already been filled.

C. As regards your application, I regret to inform you that the vacancy has already filled.

D. As regards to your application, I regret to inform you that the vacancy has already been filled.