For the Following Argument, Choose the The Best Candidate for an Implicit

For the following argument, choose the the best candidate for an implicit premise given the premises and conclusion provided. Your aim is to make the argument valid or forceful:
P1) If Frank Sinatra and Sammy Davis Jr. are at the Sands, then Dean Martin is probably playing at the Sands P2) _ C1) Probably, Dean Martin is playing at the Sands

A) Frank Sinatra and Sammy Davis Jr are probably playing at the Sands
B) Frank Sinatra and Sammy Davis Jr are at the Sands
C) Frank Sinatra is probably Sammy Davis Jr
D) Dean Martin is playing at the Sands