Which of the following is NOT correct about the base of product differentiation? Group of answer choices Firms differentiate by focusing directly on the attributes of products or services such as product features, product complexity, timing of product introduction and location. Firms differentiate by establishing relationships between the firms and their customers. Examples are product customization, consumer marketing and product reputation Firms differentiate by establishing linkages within or between firms. Examples are linkages among functions within a firm, linkages with other firms, product mix, distribution channels and service and support. Firms differentiate by focusing on learning-curves to gain efficiency over time.