I can’t find the yogurt you like

In which of these cases would you be using an encryption technology?

A) You need to make a file writable by you, but read-only for everyone else

B) You need to ensure that all data is removed from a hard drive

C) You want to provide for stateful network access

D) You want to access your office file servers and printers while traveling

E) Just pick up some encryption at the store with some milk and bananas