Comparative performance statistics—especially across competing mutual funds—are most commonly obtained from independent fund rating services, making C correct. These services compile standardized fund performance data, risk metrics, category comparisons, peer rankings, and sometimes risk-adjusted measures, allowing investors to compare funds across managers and fund families. Because they are designed specifically for cross-fund comparisons, they are the best source among the choices.

A fund’s prospectus (choice A) contains important disclosures about that specific fund—objectives, strategies, risks, fees, and past performance—but it is not primarily a comparative document across multiple competing funds. Shareholder reports (choice B) provide periodic information about a specific fund (financial statements, portfolio holdings summaries, management discussion), and while they include performance figures, they typically do not provide broad comparisons of “competing mutual funds.” The statement of additional information (choice D) supplements the prospectus with expanded technical details about that particular fund; it is not meant to be a comparative performance source across the market.

For SIE purposes, recognize the roles of fund documents: prospectus/SAI/shareholder reports are issuer-specific disclosure documents, while independent rating services are built for industry-wide comparisons. This distinction helps you answer questions about where an investor would go for peer group performance, ranking, and objective comparative data rather than reading each fund’s disclosures individually.