In order for a gear to work in a piece of machinery, the radius of the gear, r, must be greater than 4 cm, but not exceed 4.1 cm. Which compound inequality represents the situation?
a. r > 4 and r = 4.1
b. r > 4 or r = 4.1
c. r < 4 and r = 4.1
d. r < 4 or r = 4.1
