The correct answer is B. A price taker.
In perfect competition, there are many firms producing identical products. This means that each firm has a very small share of the market and cannot influence the market price. The price of the product is determined by the market forces of supply and demand, and each firm must accept this price.
A price taker is a firm that has no control over the price of its product. The price is determined by the market forces of supply and demand, and the firm must accept this price.
A valuer is a person who estimates the value of something.
Obstructing the entry of the other firms is a strategy that a firm can use to maintain its monopoly power.
Producing a commodity different from the competition is a strategy that a firm can use to differentiate its product from the products of its competitors.
In perfect competition, there are many firms producing identical products, so there is no need for firms to differentiate their products.