For Air Methods aircraft operating under IFR, how frequently is a VOR operational check conducted, and what is the specific check interval for VFR operations?
A) 1. IFR: Every 30 days; VFR: Every 60 days
B) 2. IFR: Every 90 days; VFR: Every 180 days
C) 3. IFR: Every 60 days; VFR: Every 120 days
D) 4. IFR: Every 45 days; VFR: Every 90 days