Answer:
The salutation is the part of the letter that needs revision in order to be appropriate for a formal letter.
Step-by-step explanation:
The salutation of a letter needs to have an expression to greet the person, in this case, being the letter written in formal context, the correct expression would be Dear Mrs. Parker instead of just saying Mrs. Parker, this part of the letter is very important since it is the introduction to the rest of the document.