A firm can vary supply of product by controlling

A) production capacity and inventory.
B) production capacity and price promotions.
C) price promotions and inventory.
D) production capacity and inventory promotions.

A firm can control the supply of a product by adjusting its production capacity and inventory levels. By increasing or decreasing the capacity of production, a company can alter the amount of product it can produce in a given time frame. Similarly, by managing inventory levels, a firm can regulate the amount of product it offers in the market. Price promotions may affect demand for the product but do not directly control the supply.