What is a written document that serves as a guide for the marketing manager's activities?

The correct choice is indeed the marketing plan, as it is a comprehensive written document that outlines the marketing strategies and tactics a company will use to achieve its marketing goals. A marketing plan typically includes details on target markets, marketing research, budget, and action plans for various marketing activities. It serves as a strategic guide for marketing managers to ensure that their efforts are aligned with the overall business objectives.

The other terms mentioned have specific meanings that do not align with the comprehensive nature of a marketing plan. A marketing blueprint may suggest a structural approach or framework, but it does not encapsulate the detailed action-oriented content found in a marketing plan. A marketing proposal usually refers to a document that seeks approval for specific marketing initiatives, and a marketing report provides analysis and outcomes of marketing activities rather than guidance for future actions. Therefore, the marketing plan stands out as the essential document for guiding a marketing manager's activities effectively.