Error handling and Boundaries

According to the book which of the following is one reason why exceptions are preferred to error codes?

It is ok to return NULL from a function

Checked exceptions are always superior to unchecked exceptions

Code readability and error handling are always conflicting, and this can't be solved

Every interface is a boundary

It is a waste to write tests for third party code as it is already well tested

It is a bad idea to expose the internal data structures in an interface at the boundary

We should not start writing code till the final interface is known, even when we have an idea of what our interface should look like