I think the wording on C is just a little confusing. If you are asking for "reduced Planck('s) constant," then having the last sentence in C. just muddies the waters (in my opinion). Almost reflexively, I complete it with "Planck('s) constant," even though that is clearly not what is being asked. I would change the last sentence to "it equals a related constant over 2-pi" or something like that. That way, you don't say reduced or Planck constant, but can still accept the entire answer space desired. From the 20-20 hindsight department.
(plus I realize I missed the post right before this one that said essentially the same thing... paying attention helps, Steve).
Also, my little bugbear with the lead-in is that Heisenberg's principle, if I remember correctly, states that one cannot simultaneously know momentum and position (as one such pair)
with infinite precision.