Determine the parametric form of a closed curve r(t), moving from the origin (0,0) along a straight line to (2,4) and returning to the origin along y= -(x-2)² + 4.
a) r(t) = (2t, 4t); 0 ≤ t ≤ 1
b) r(t) = (2t, 4t); 0 ≤ t ≤ 2
c) r(t) = (2t, 4t - 8t² + 8t); 0 ≤ t ≤ 1
d) r(t) = (2t, 4 - 8t² + 8t); 0 ≤ t ≤ 1