Final answer:
The advertising budget and product sales increase rapidly during the Introduction and Growth stages of the product life cycle due to efforts to build awareness, differentiate the product, and encourage market penetration.
Step-by-step explanation:
The advertising budget and product sales both tend to increase rapidly during the Introduction and Growth stages of the product life cycle. During the Introduction stage, the goal of advertising is to build awareness and to encourage the adoption of the new product. This is often a period of substantial investment in marketing and advertising. As the product moves into the Growth stage, the focus of advertising shifts to differentiating the product from competitors and encouraging greater market penetration. Sales typically increase rapidly as a result of these efforts because the product begins to gain acceptance, the target population likely to buy rises, income may rise, and the price of substitutes may rise, driving consumers to the new product.