which best illustrates the distinction between statistical significance and practical importance

a) in 2016 240 out of 400 statistics students at Oxnard technical college sold their textbooks at the end of the semester compared with 220 out of 330 students in 2015 significant decrease

b) our new manufacturing technique has increased the life of the 80 GB USB asimoDrive external hard disk significantly from 240,000 hours to 250,000

c) in 50,000 births the new vaccine reduced the incidence of infant mortality in Morrovia significantly from 1402 deaths per 1000 births to 10.3 deaths per 1000 births