Answer:
d. $12.00 and up to $15.00
Step-by-step explanation:
The hourly earnings classes and their respective frequencies are presented bellow:
[tex]\begin{array}{cc}wage&frequency\\\$6\ to\ \$9&16\\\$9\ to\ \$12&42\\\$12\ to\ \$15&10\\\end{array}[/tex]
The least occurring class is the $12 to $15 with 10 occurrences.
Therefore, the limits of the class with the smallest frequency is d. $12.00 and up to $15.00