I can't seem to figure out why there is changes. How would I go about this answer? Or what is the reasoning?

Q: The amount of labour required to produce a product changes as the quantity produced of that product increases. Below is a graph of the labour costs to produce a product. Explain, using the appropriate economic terms, why the costs are changing in each section. Provide your answer in the following format: A - answer, B - answer. $1,200.00 - Average Labour Costs per Unit $1,000.00 $800.00 $600.00 $400.00 $200.00 1 5 10 15 20 25 30 35 40 45 50 55 60 65 Quantity (Q) Answer: Check