Which is true about the & and && prefixes with substitution variables?

& can prefix a substitution variable name only in queries. DML

An & prefix to an undefined substitution variable, which is referenced twice in the same query, will prompt for a value twice .

The && prefix will not prompt for a value even if the substitution variable is not previously defined in the session.

An && prefix to an undefined substitution variable, which is referenced multiple times in multiple queries, will prompt for a value once per query.

Both & and && can prefix a substitution variable name in queries and DML statements.