If a Partnership Does Not Want to Abide by the Default

If a partnership does not want to abide by the default rules promulgated by the RUPA and/or the UPA, the partners

A) Are out of luck as the default rules are mandatory.
B) Can override the default rules by judicial decree.
C) Can override the default rules by a partnership agreement.
D) Are out of luck as modifying default rules is criminal misconduct.