Average Total Cost Rises from 10 to 20 Units Steps:

• Calculate ATC at 10 units: (TFC + TVC) / output = (300 + 80) / 10 = 38.
• Calculate ATC at 20 units: (300 + 1500) / 20 = 90.
• Compare ATC values: rises from 38 to 90 over the output range.
• Conclude behavior: continuous increase with given data.

Why C is correct:

• ATC formula (total cost / output) yields increasing values from 10 to 20 units, showing continuous rise due to variable costs increasing faster than fixed costs spread.

Why the others are wrong:

• A: ATC increases, does not fall.
• B: Only two points provided; no fall observed before rise.
• D: No initial rise followed by fall; monotonic increase.

Final answer: C