Final answer:
To ship remains across the country, a transportation permit along with a death certificate is required. State-specific regulations may vary, but these documents are generally necessary. Therefore the correct answer is Death certificate.
Step-by-step explanation:
When shipping remains across the country, the document that is typically required is a transportation permit. Additionally, a death certificate is generally necessary to obtain the transportation permit. It's important to check specific state regulations as they can vary, but generally, both the death certificate and the transportation permit are needed to transport remains, whether they have been embalmed or not. Hence, the correct option is Death certificate.