The correct answer is A. 1,033.
To break even, the total revenue must equal the total cost. The total cost is the sum of the fixed cost and the variable cost. The fixed cost is P428,000, and the variable cost is P115 + P76 + P2.32 = P203.32 per unit. Therefore, the total cost per unit is P203.32 + P428,000/x = P600, where x is the number of units that must be manufactured each month to break even. Solving for x, we get x = 1,033.
Option B is incorrect because it is the total cost per unit. Option C is incorrect because it is the total variable cost per unit. Option D is incorrect because it is the total fixed cost per unit.