A: If you set the selling price to $1.50 per unit and spend $0 on advertising, you will sell 140 units per day. B: If you reduce the selling price to $1.20 per unit and spend $0 on advertising, you will sell 210 units per day. C: If you set the selling price to $1.50 per unit and spend $30 per day on advertising, you will sell 210 units per day