Let f be a function such that f (1) = 2. At each point (x, y) on the graph of f, the slope is given by 2 = 5xy - x2 - y2 - 5. Which of the following statements is true? A f has a relative minimum at x = 1. B of has a relative maximum at x = 1. C f has neither a relative minimum nor a relative maximum at x = 1. D There is insufficient information to determine whether f has a relative minimum, a relative maximum, or neither at x = 1