The requirement to have a GPWS aboard commences at what MCTOW and authorized passenger configuration?
a) MCTOW greater than 12,500 lbs and authorized for 10 or more passengers
b) MCTOW greater than 15,000 lbs and authorized for 6 or more passengers
c) MCTOW greater than 6,000 lbs and authorized for 20 or more passengers
d) MCTOW greater than 10,000 lbs and authorized for 9 or more passengers