Outsider Industries S.a.r.l. is a company that is organized in Luxembourg. It is not a per se corporation for U.S. tax purposes. Under Luxembourg law, no member of a S.a.r.l. has unlimited liability. If Outsider Industries S.a.r.l. has three owners, what is its default entity classification for U.S. tax purposes under the "check-the-box" regulations?

a) Corporation

b) Partnership

c) Disregarded entity

d) None of the above