Final answer:
Product tie-ins, contests, and sweepstakes fall under sales promotions. Tying sales, part of sales promotions, involve purchasing one product to buy another, which can limit consumer choice and force unwanted purchases.
Step-by-step explanation:
Product tie-ins, contests, and sweepstakes are types of sales promotions. These promotional strategies are implemented to boost sales, engage consumers, and increase brand awareness. Tying sales, a form of sales promotion, involve a condition where a customer can buy one product only if they also buy another product. This strategy is controversial as it may force consumers to purchase items they don't want or need, and it can restrict consumer choice.
For example, a requirement to purchase a specific portable TV model to buy a popular DVD would be somewhat unrelated and could be seen as unfair to customers who might not want that particular TV model or who might prefer to choose from a wider selection of models available in the market.