Consider the following parametric equations. a. eliminate the parameter to obtain an equation in x and y. b. describe the curve and indicate the positive orientation. a. eliminate the parameter to obtain an equation in x and (type an equation.) b. choose the correct answer below. o a. the curve is a line going up and to the right as t increases. o b. the curve is a line going down and to the left as t increases. o c. the curve is a parabola that opens upward. o d. the curve is a parabola that opens downward.