Part A:
If a quadratic has only one x-intercept, then that is where the vertex lies. being that the vertex is the highest or lowest point in the quadratic. To sketch, it will open downwards with a single x-cept
Part B:
The graph will be above the x-axis. And having the vertex being at (0,1) as it says its the minimum value. All the minimum means is that its the lowest value of this given parabola.
Part C:
Plot the points of the y-intercept and z-intercepts. Then plot the maximum value is. Connect the dots.