The correct option is B Jargon
'Words used by a profession or group, difficult for others to understand' is called Option B, Jargon. Option A, 'Rhetoric' means the art of persuasive writing or speaking. Option C, 'Pedantic' means giving too much attention to small details. Option D, 'Verbatim' means exactly or literally. Thus, options A, C and D are incorrect and the correct word for the given phrase is Option B, Jargon.