Final answer:
James earns $500 in one week as a welder.
Step-by-step explanation:
In one week, James works 8 hours per day, Monday through Friday. So the total number of hours worked in one week is 8 hours/day x 5 days/week = 40 hours. James earns $500 in one week as a welder.
James earns $12.50 per hour, so his weekly earnings can be calculated by multiplying his hourly rate by the total number of hours worked: $12.50/hour x 40 hours = $500.
Therefore, James earns $500 in one week, so the correct answer is D) $500.