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 9.6 mean in the context of this equation?

a)his friends on average studied 9.6 hours.

b)if they studied 9.6 hours they would get a 0 on the test.

c)they should study 9.6 hours in order to get an a on the test.

d)for every hour they studied their grade would go up 9.6 points.