A company is researching the effectiveness of a new web site design to decrease the time to access a website. Five web site users were randomly selected and their times (in seconds) to access the web site with the old and new designs were recorded. The results follow. User OLD NEW A 30 25 B 45 30 C 25 20 D 32 30 E 28 27 Clearly, the old website is slower than the new. What is the null hypothesis? (a) H0: µd = 0 (b) H0: µd ? 0 (c) H0: µd ? 0 (d) H0: µd ?