Final answer:
The person responsible for developing and implementing the marketing plan for a single brand is the Brand manager.
Step-by-step explanation:
The individual who is responsible for developing and implementing the marketing plan for a single brand is the Brand manager. They are in charge of all aspects of a brand's marketing strategy, including market research, product development, advertising, and promotion.
Brand managers work closely with various teams such as sales, advertising, and product development to ensure the success of the brand.