in a professional email, you should not use emoticons there as it looks unprofessional. so A is incorrect. the domain is who you are, and who the letter is from. B just doesn't make sense. C the subject line is correct. The subject line is the part that you should try to be brief but highly descriptive. Software that people commonly use in the workplace to make their lives easier. D the bcc is when you are wanting to copy someone else's writing in a word document or on paper. this option does not make sense either.
