Respuesta :
This letter was very emotional, personal and non-formal. Memories of the past were brought up and no critiquing of the paintings as a professional would do. Different punctuation used to convey emotion since there is an emotional, familial connection as opposed to a professional connection.
A. Its language is informal.
Informal language is best suited for communications to friends, self (such as journal entries), and family. Informal language can be used for almost anything other than professional (business/academic) settings. Because this letter is a thank you letter to her aunt and about a non-professional event (the gifting of a personal painting), informal language is certainly appropriate here.