John drank 6 12-ounce beers from 9 p.m. to 12 a.m. How many drinks still remain in his bloodstream?

To determine the number of drinks that still remain in John's bloodstream, we need to consider the rate at which the body metabolizes alcohol. On average, the human body metabolizes alcohol at a rate of about one standard drink per hour.
John consumed a total of 6 beers, with each beer being 12 ounces. Therefore, he consumed a total of 6 * 12 = 72 ounces of beer.
Since John drank from 9 p.m. to 12 a.m., he consumed the beers over a span of 3 hours.
Assuming that each 12-ounce beer is equivalent to one standard drink, John consumed 72 / 12 = 6 standard drinks.
Considering the average rate of alcohol metabolism of one standard drink per hour, by the time it is 12 a.m., John's body would have metabolized 3 hours * 1 drink per hour = 3 standard drinks.
Therefore, 6 - 3 = 3 drinks remain in John's bloodstream. So the correct answer is 3.