(b) 1
The number of zeroes of f(x) is 1, as the graph touches (or crosses) the x-axis at exactly one point.
The zeroes of a polynomial are the x-coordinates of points where its graph intersects the x-axis. The described W-shaped curve touches the x-axis at only one point (tangentially), giving exactly 1 zero. Examiner looks for correct identification of intersection/touch points with the x-axis.