Which combined practice best prepares a Pennsylvania applicant for the CDL Doubles/Triples endorsement test and safe operation?

1. Study PennDOT CDL Manual Section 7, know federal T endorsement topics, and practice coupling, inspection, air-line, and stability questions
2. Study only passenger bus evacuation rules
3. Memorize only Pennsylvania car-license signs
4. Rely only on a competitor practice-test answer key