transfer pricing

HI i need help with this question.the answer GIVEN is A.How should i work out this calculations? im lost
ROCK has two divisions Division P and Division Q. Division P produces product X, which it sells to external market and also to Division Q. Divisions in ROCK operate as investment centre and divisions are given autonomy to set transfer prices. Division P must transfer to Division Q in priority of external customers.

Performance of each division measured on the basis of target profit given for each period. Division P has been given a profit target of $50,000,000 for the year.

Division P can produce 200,000 units of product X at full capacity. Demand for product X in the external market is for 140,000 units only at selling price of $5,000 per unit.

To produce product X Division P incurs $3,200 as variable cost per unit and total fixed overhead of $80,000,000.

Division Q has requested a quotation for 80,000 units of product X from Division P.

Required

Calculate the transfer price per unit of product Z that Division W should quote in order to meet target profit for the year?
A. $2,125

B. $3,200

C. $5,000

D. $4,500