There are four errors in C:

1. "Due to" is used wrongly - should be "because of".
2. "Advice" does not take subjunctive - it takes infinitive.
3. Moreover for a command subjunctive, active voice is preferred because the advice/ demand is applicable on the subject of the action.
I demand that you pick up the phone.... correct
I demand that the phone be picked up.... not preferred
Thus in C, "...advice that the inventory be marked up..." in not preferred.
4. The advice to mark up is not to meet the speculation, but to meet the problem itself. Wrong meaning is conveyed by the construction "meet a sever winter and the speculation".

E in my opinion is the best of the lot, though it contains the errors 1 and 4 mentioned above.