A quadrilateral with vertices at $(0,-1)$, $(3,1)$, $(3,-1)$, $(0,1)$ is $a$ ________.

Step 1 (Vertices and Plotting): We plot the given coordinates in the 2D Cartesian plane:

• $A(0,1)$

• $B(3,1)$

• $C(3,-1)$

• $D(0,-1)$

Step 2 (Side Lengths and Slopes): We compute the distance between consecutive points:

• $AB=\sqrt{(3-0{)}^2+(1-1{)}^2}=3$ (horizontal segment along $y=1$)

• $BC=\sqrt{(3-3{)}^2+(-1-1{)}^2}=2$ (vertical segment along $x=3$)

• $CD=\sqrt{(0-3{)}^2+(-1-(-1){)}^2}=3$ (horizontal segment along $y=-1$)

• $DA=\sqrt{(0-0{)}^2+(1-(-1){)}^2}=2$ (vertical segment along $x=0$)

Step 3 (Identify Shape): Opposite sides are parallel and equal in length ($AB=CD=3$ and $BC=DA=2$). Adjacent sides are perpendicular because one is horizontal and the other is vertical, forming $90^{\circ }$ angles. Since the adjacent sides are unequal ($3\ne 2$), the shape is a rectangle.

Step 4 (Conclusion): This corresponds to index 3 in the options ['kite', 'square', 'parallelogram', 'rectangle']. The correct answer is option index 3.