The correct answer is C) either active or passive. Technicians servicing small refrigeration appliances can employ either active or passive refrigerant recovery equipment. The Clean Air Act and EPA regulations require that technicians properly recover refrigerants from appliances to prevent their release into the atmosphere. Both active and passive recovery methods are acceptable ways to comply with these regulations and capture the refrigerant for reuse or proper disposal. The other options are incorrect. Option A is incorrect because passive recovery alone is not sufficient - active recovery equipment is also an acceptable method. Option B is incorrect because both active and passive recovery are permitted. Option D is incorrect because there is a requirement to recover the refrigerant, not simply vent it to the atmosphere.