A firm using a departmental overhead rate has four departments with the following overhead amounts: $400,000, $600,000, $200,000, and $400,000. The same departments respectively have the following annual labor-hours totals: 60,000, 80,000, 40,000, and 20,000. Assuming that labor-hours are used as the allocation base, what overhead rate will the first department use?

a) $2/labor-hour

b) $6.67/labor-hour

c) $8/labor-hour

d) $10/labor-hour