Which sentence best demonstrates the language required of an argumentative speech?
college entrance exams are super important to colleges, and every student must work hard to get a decent score.
every high school in the county must provide its students with thorough information about college entrance exams.
high school guidance counselors are a good source of information about college entrance requirements.
students often take preparatory classes to up their scores on college entrance exams.

The sentence that best demonstrates the language required for an argumentative speech is the following one: Every high school in the county must provide its students with thorough information about college entrance exams.  This is the case because the language used is formal: the tone, the words and the ways the words are put together are the elements that make up this formal style. As we are talking about an argumentative speech, the word choices should be compatible with this writing style. For instance, the sentence contains "provide" instead of "give", an adjective such as "thorough" and "entrance" instead of "admission".