If a Pretrial Motion to Suppress Evidence Is Filed in Federal

If a pretrial motion to suppress evidence is filed in federal court, who bears the burden of proving the reasonableness of the search?

A) If the search was based on a warrant, the burden of proof falls on law enforcement.
B) If the search was based on a warrant, the burden of proof falls on the defendant.
C) If the search was conducted without a warrant, the burden of proof falls on the defendant.
D) The burden of proof falls on law enforcement whether the search was conducted with or without a warrant.