A function accepts &str and receives &Box<String> through deref coercion. What happens to…

A function accepts &str and receives &Box<String> through deref coercion. What happens to ownership?

1. The function borrows the string; the caller keeps ownership of the Box.
2. The String moves out of the Box and into the function.
3. The Box is cloned and a reference count is incremented.
4. The heap allocation is converted into static storage.