Georges asked five of his friends how long they studied for the last math test and what grade they received. He found a linear regression equation for the data to be y = 9.6x + 65.8. What does the 65.8 mean in the context of this equation? A) If they studied 0 hours they would earn a 65.8. B) The lowest grade of his five friends was a 65.8. C) The lowest grade they could receive on the test was a 65.8. D) For every hour they studied their grade would go up 65.8 points.