Answer
$(a)$ See the Red graphs on the image below.
$(b)$ See the Blue graphs on the image below.
$(c)$ Value of $c$ shifts the graph of $x^2$ either upward or downward by $c$ units.
Work Step by Step
The base of the function $x^2$ has a form of the Black graph on the image above.
$(a)$ See the Red graphs on the image above.
By addition, the graph is moving upward by $c$ units.
$(b)$ See the Blue graphs on the image above.
By subtraction, the graph moves downward by $c$ units.
$(c)$ Value of $c$ shifts the graph of $x^2$ either upward or downward by $c$ units.