Where did you take this question from? F(x) is a function of one variable so if THE tangent line at some point of the graph of F(x) exists then it is unique since its slope is given by the value of F'(x) at the x-coordinate of the tangency point. How can they ask something about "tangent lineS" at some point on the graph??

This must be a mistake or else this book's teaching stuff which I believe is not standard.

Tonio