What ethical consideration should a private investigator prioritize when using technology for surveillance (e.g., GPS trackers, hidden cameras)?

1. Obtaining a warrant for all surveillance activities, even if not legally required.
2. Ensuring the technology's use is legal, justified by the investigation's legitimate purpose, and minimizes intrusion into privacy.
3. Prioritizing cost-effectiveness over privacy concerns if the information is critical.
4. Using the most advanced and discreet technology available, regardless of legal implications.