yes. That is True. A buisness letter is formal, and uses profession writing and formatting. A friendly letter is playful, and does not need to be formal, and respectful. (In writing terms) A buisness letter is professional and serious. It is True.
~Silver
The answer is B, subject and predicate.
The answer is b I hope this helps
Definitely not b or c; it feels most like a, in my opinion.