The correct answer is (A).
Getting to the Answer: Translate the words in the question into an algebraic equation. Profit equals the difference between the sales revenue and the variable cost to produce each boat, minus the one-time fixed cost. Each boat sells for $20,000 and costs $7,000 to produce, so each boat's contribution to profit is $20,000-$7,000=$13,000. The total contribution to profits will be $13,000 times the number of boats sold, which is x. The $10,000,000 initial investment must be subtracted from the profits, so the realized profit, in dollars, is 13,000x-10,000,000.
(A) Correct: this matches the correct calculation
(B) Incorrect: this calculates the profit per boat sold as the sum of the price and the cost
(C) Incorrect: this is the initial investment ($10,000,000), less the sum of the price and cost per boat ($20,000 + $7,000), times x
(D) Incorrect: this is the revenue from the sales of the boats
(E) Incorrect: this is the profit from the sales but omits the initial investment