Let d=(golf score after using the newly designed golf clubs)-(golf score before using the newly designed golf clubs). Use a significance level of alpha =0.05 for the test. Assume that the scores are normally distributed. What is the null hypothesis for this test?
1) H0: d = 0
2) H0: d > 0
3) H0: d < 0
4) H0: d ≠ 0