Selling is the correct answer in this case.

Explanation:
- Selling refers to the process of exchanging a product or service for money or other goods, and it typically occurs after the product has been developed.
- The development of a product involves designing, manufacturing, and testing it to ensure that it meets the desired specifications and quality standards.
- Once the product has been developed, it needs to be sold to customers in order to generate revenue and make a profit.
- Selling activities include identifying potential customers, reaching out to them, presenting the product, negotiating prices, and closing the sale.
- These activities may involve direct selling, such as through sales representatives or in retail stores, or they may involve indirect selling, such as through online platforms or distributors.
- Selling is an essential part of the marketing process because it directly contributes to the company's revenue and profitability.
- However, it is important to note that selling is just one aspect of marketing.
- Marketing encompasses a broader set of activities that are aimed at creating, communicating, delivering, and exchanging offerings that have value for customers, clients, partners, and society at large.
- Marketing activities typically start before the product has been developed, as they involve conducting market research, identifying customer needs and preferences, and developing a marketing strategy.
- Publicity is a subset of marketing activities that involves promoting a product or brand through various media channels to create awareness and generate interest.
- While publicity can play a role in selling a product, it is not exclusive to selling and can occur at various stages of the marketing process.
- Therefore, selling is the most appropriate answer to the given question, as it specifically refers to activities that occur after the product has been developed.