Q22

[mcrittell]

I couldn't choose between D and E because I thought that C could fly with F, B with D, and E with A.

[maryadkins]

The trick here is that we don't have to have a copilot on every plane (if you look back at the constraints, you'll see we're only told there has to be a qualified pilot on every plane). So you're right that D will have to fly with B because D can't fly with A, but E could also fly with B and A could fly by herself.