Explanation: a suffix is a morpheme (a letter or group of letters) added at the end of a word to form a derivative or change the meaning of the initial word. From the given options, the suffix that would be added to "earl" to create the meaning "domain of an earl" or "land rule by an earl" is the corresponding to option B: "dom" which can form nouns which refer to domain (like kingdom), collection of persons, rank or station, or general condition (like freedom). So the word would be "earldom."
The salutation is to greet the person you are addressing, it goes before the introduction. The introduction is a brief summary of the letter itself and the body is the letter itself.
