What is the slope of the line tangent to f(x) = –x2 + 4 at x = –3?

The slope of the tangent line is given by the derivative. For f(x) = −x² + 4, f′(x) = −2x. Substituting x = −3 gives f′(−3) = −2(−3) = 6, so the slope is 6 (choice C).

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