f. Skills! Because every single ability you have can be spun as a job in case of need! You can always cook, clean, care for others' children (as well as your own), fix things or make things for others, and so on. The fact that my parents took us camping for every vacation and that I was good with kids (possibly due to helping with my sisters and their friends) probably helped me get a summer camp job. I got to hike, climb, kayak, and raft all over Northern California on the camp's dime for 2 months, I just had to watch 15 teenagers while I was at it. Much preferable to being stuck behind a counter or a desk that whole time. I'm pretty sure I got my scholarship to college primarily because I told my interviewer that I went on a 48 mile, 2 day hike a month previously due to not wanting to miss that opportunity. Basically, skills = options!
But if we're talking material/financial, I'll go with c. cash for college. I'm thinking set amount to pay college expenses as necessary and then they get remainder (if any) upon graduation. OR they present an alternative business/education plan and get the money if it's feasible. Granted, these are 2+ years down the road hypothetical children.