When a Patient Has Both Medicare and Medicaid

When a patient has both Medicare and Medicaid,

A) you need to prepare two forms and file with Medicare first.
B) claims are automatically forwarded from Medicare to Medicaid.
C) claims no longer need to be filed on a CMS-1500.
D) you need to file with Medicaid and Medicare at the same time, dividing the claim amounts equally.
E) you need to file the claim with Medicaid first and then with Medicare.