An ordered n-tuple (d1, d2,…, dn) and d1 ≥ d2 ≥ … ≥ dn is called graphic if there exists a simple undirected graph with n vertices having degrees d1, d2,…, dn respectively. Which of the following 6-tuples is NOT graphic?

• A. (1, 1, 1, 1, 1, 1)
• B. (2, 2, 2, 2, 2, 2)
• C. (3, 3, 3, 1, 0, 0)
• D. (3, 2, 1, 1, 1, 0)