Cost per head = $600 / 1500 = $0.40
On the first day, 2/3 of the heads were sold at a price 25% above the cost per head:
Selling price per head on the first day = $0.40 + 0.25($0.40) = $0.40 + $0.10 = $0.50
The revenue from selling 2/3 of the heads on the first day can be calculated as:
Revenue on the first day = (2/3) * 1500 * $0.50 = 1000 * $0.50 = $500
On the second day, the remaining 1/3 of the heads were sold at a price 10% less than the price per head on the first day:
Selling price per head on the second day = $0.50 - 0.10($0.50) = $0.50 - $0.05 = $0.45
The revenue from selling the remaining 1/3 of the heads on the second day can be calculated as:
Revenue on the second day = (1/3) * 1500 * $0.45 = 500 * $0.45 = $225
The gross profit can be calculated by subtracting the total cost of the shipment from the total revenue:
Gross profit = ($500 + $225) - $600 = $725 - $600 = $125
Therefore, the gross profit on this shipment is $125, which corresponds to option (C).