In this question it is given that
Carla earns $8.43 per hour. It means that her hourly rate is $8.43 .
And we have to find her overtime pay at time-and-a-half.
First we have to understand what time and a half means .
Time and a half means 1.5 times of the normal rate. And to find the overtime pay, we have to multiply 1.5 and normal hourly rate. That is
[tex]=1.5*8.43 = $12.65[/tex]
Therefore correct option is a .