What is meant by a product differentiation strategy?

A firm merges with another company in the same line of business.
A firm introduces a new product feature that other products in the market do not have.
A firm reduces its costs of production by using new production technology
A firm sells its product at a price below the current market price, even if it makes a loss.

Explanation
Under a product differentiation strategy, a firm will seek a competitive advantage by making its products less substitutable and reducing the price elasticity of demand.