Which statement about `public required string Name { get; init; }` is correct?

Which statement about `public required string Name { get; init; }` is correct?

1. Normal C# creation code must assign Name, and ordinary assignment is rejected after construction, but runtime null validation is still separate.
2. The runtime guarantees Name can never be null.
3. The declaring type can never modify any object referenced by Name.
4. Every constructor body is verified to assign Name.