The core concept here is the flexibility in academic writing. The correct answer, C, suggests that new relevant ideas should be incorporated into the draft, which aligns with the principle of not being constrained by the outline. Option A is incorrect because it advocates for rigidity, which goes against the principle of flexibility. Option B is wrong because it suggests a lack of structure, which is not conducive to organized writing. Option D is incorrect because it recommends excluding new ideas, which could be valuable to the draft.