Determine from the graph whether f possesses extrema on the interval (a,b).
Maximum is at the x=c, and minimum at x=b???
Unfortunately, there is no way to answer the question based on the drawing; if the graph were of a better quality then maybe.
For example, in we know absolutely that then you could say that is a extreme maximum. But that is not clear from your drawing.
The second problem with the question is that the notation is a open interval. Thus, there would be no minimum at because is not in the domain of interest. If however it were , a closed interval, the would be the absolute minimum,