Answer:
B. a switchboard
Step-by-step explanation:
Bound forms are linked to a record source like a database, query or table, can be used to add or edit data in the record source.
Unbound forms are forms that are not bound to any database, query or table but that does not mean it cannot have data,the data is brought in manually, where a bound form is automatically associated with some data.
A switchboard form is an unbound form due to this any data that is changed in your switchboards form don't have any effect on the same data in the Access database.