A function has a relative maximum at x = c when:
✓ Correct Answer: Option B
By the second derivative test: if f'(c) = 0 and f''(c) < 0, the function is concave down at c → local maximum.
By the second derivative test: if f'(c) = 0 and f''(c) < 0, the function is concave down at c → local maximum.