Which of the following sentences does NOT share the same register as the others?

'Register' means the tone and level of formality of language. Whether speaking or writing, you must always choose the register appropriate to your audience and purpose. Standard English is always appropriate to formal situations, as well as many informal situations (for example when addressing people you do not know). At other times, fine judgment must be used. You should consider the age and background of your expected audience along with your purpose in writing or speaking.