Which score indicates the highest relative position?
a.a score of 630 on a test with mean 800 and s = 200
b.a score of 3.2 on a test with mean 4.6 and s = 1.5
c.a score of 43 on a test with mean 50 and s = 5
d.a score of 43 on a test with mean 55 and s = 5