The economic order quantity refers to: Question 19 options: 1) The number of units that the firm purchases in a year. 2) The quantity of goods that the firm orders every time it places an order. 3) The total yearly costs of ordering a set number of items on a regular basis. 4) The per-order costs of ordering a fixed quantity every time the firm places an order. 5) The sum of ordering and holding costs for the quantity of goods that the firm orders