Question: Below is the graph of a function on which four points have been labeled. Which of the following statements about these points is true?
![953_7.gif](https://secure.tutorsglobe.com/CMSImages/953_7.gif)
- The derivative of the function at point A is positive.
- The derivative of the funtion at point B does not exist.
- The derivative of the function at point C is zero.
- The derivative of the funtion at point D is negative.