Final answer:
Line B, 'The stars reveal this, the mighty oak and the rose, / The flinty rocks I skipped across a brook,' best supports the answer to Part A.
Step-by-step explanation:
The best line that supports the answer to Part A, which states 'Be true to yourself,' is line B. 'The stars reveal this, the mighty oak and the rose, / The flinty rocks I skipped across a brook.' This line suggests that nature itself expresses the idea of being true to oneself. It emphasizes the importance of staying connected to one's own true nature and not being swayed by external influences.