Per MUTCD 2003 Section 2A.18, if a secondary sign is mounted below another sign on a freeway or expressway, the major sign shall be installed at least which heights above the pavement edge?

1. Both signs at 5 ft
2. Major sign at 7 ft and secondary sign at 1 ft
3. Major sign at 17 ft and secondary sign at 12 ft
4. Major sign at least 8 ft and secondary sign at least 5 ft