Final answer:
The minimum transfer price for the Heating Division should be at least the contribution margin of $18 per unit, to cover the opportunity cost of not selling the units externally.
Step-by-step explanation:
The minimum transfer price for the Heating Division of Kobe International should be set based on the opportunity cost of transferring the units internally rather than selling them externally at the market price. Since the Heating Division is operating at full capacity, the opportunity cost is the contribution margin it would earn on sales made externally. This contribution margin is calculated as the selling price minus the variable cost, which is $39 - $21 = $18 per unit. Considering this, the minimum transfer price that the Heating Division should accept for transferring 14,900 heating units internally should be at least $18 per unit, to cover the lost contribution margin on external sales.