In Which of the Following Situations Is a Search Warrant

In which of the following situations is a search warrant necessary?

A) To attach a tracking device to the undercarriage of the suspect's car vehicle while it is parked on a public street and use the device to track the suspect's public comings and goings.
B) To videotape a drug deal in a suspect's home by equipping an informer with a concealed video camera.
C) To walk a drug-detection dog down a motel corridor and perform a sniff at every door.
D) None of the above.