Della Company received an offer from an overseas customer to purchase 1,000 units at $250 per unit. The special offer will not endanger its ability to care for existing customers, who currently pay $300 per unit. Della's fixed and variable expenses are variable manufacturing costs of $100 per unit, fixed manufacturing costs of $85 per unit, variable selling and administrative costs of $18 per unit, and fixed selling and administrative costs of $23 per unit. The units must be manufactured with the usual selling and administrative costs. In addition, there would be a shipping and handling cost of $35 per unit. Could you identify the cost(s) that is (are) relevant to this decision? 

A. Shipping and handling costs of $35 per unit. 

B. Fixed manufacturing costs of $85 per unit 

C. Fixed selling and administrative costs of $23 per unit 

D. Variable manufacturing costs of $100 per unit 

E. Variable selling and administrative costs of $18 per unit