Select all that apply.
what is the normal use of informal 1?
a)letter to friends
b)job interview
c)letter to the editor
d)phone conversation with father

The normal use of informality is letter D: phone conversation with father. Letter to friends could be either formal or informal depending on the closeness or status of the friends. Job interview, of course needs formalities because you are applying for something which is related to corporation. Letter to the editor must be formal, because you are giving out you opinion in a published article or other types of medium where everyone can read and pick insights on your write up.

D) phone conversation with father

A letter, no matter who it's written to, is done in a formal way.
A job interview will require formality because you want to show that you are educated.
A letter to an editor would be formal because you want to convince the editor.