A pilot flies VFR level cruise on a magnetic course of 270 degrees. The flight is above 3,000 feet AGL and below 18,000 feet MSL. Which altitude is correct?

1. 17,500 feet MSL
2. 26,500 feet MSL
3. 37,000 feet MSL
4. 46,000 feet MSL

Source: 14 CFR Part 91, § 91.159 VFR cruising altitude or flight level.