B

Explanation:
The correct answer is B, Government statistics. Strategic management information, used for long-term planning and high-level decision-making, often relies on external sources to understand market trends, economic conditions, and regulatory environments. Government statistics provide reliable, external data on these factors, making them a key source. Management reports (A), sales systems (C), and on-the-spot observation (D) are primarily internal sources of information, as they are generated within the organization, and thus are not typically considered external sources for strategic management information.