Which two field types need to be added to the case object to allow additional recipients on the e-mail alert?

Universal Containers requires e-mails to be sent to additional recipients when a workflow e-mail alert is triggered from the case object.

Which two field types need to be added to the case object to allow additional recipients on the e-mail alert? (Choose two.)
A . Text field
B . E-mail field
C . Lookup field
D . Formula field

Answer: BC