Answer:
The correct option is b.
Step-by-step explanation:
It is given that you earn $10.00 per hr.
Principal amount = $4,000.00
Rate of interest = 5%
Time = 1 year
Formula for simple interest:

where, P is Principal, r is rate of interest and t is time in years.
Substitute P=4000, r=0.05 and t=1 in the above formula.


The interest earn in a year is $200.
1 hr = $10.00

The interest earn in a year in terms of hours of work is 20 hrs.
Therefore the correct option is b.