Answer: The base is 4 units and the height is 9 units.
Step-by-step explanation: To find the dimensions of the rectangle, we can use the coordinates of the points A, B, C, and D. The base of the rectangle is the distance between the points A and B, or the distance between the points C and D. We can find this distance by subtracting the x-coordinates of the points: 1 - (-4) = 5. Therefore, the base of the rectangle is 5 units.
Next, we can find the height of the rectangle by subtracting the y-coordinates of the points A and C, or the points B and D. We can do this by subtracting the y-coordinates of the points: 8 - (-1) = 9. Therefore, the height of the rectangle is 9 units.
Therefore, the dimensions of the rectangle are a base of 5 units and a height of 9 units, so the correct answer is A; The base is 4 units and the height is 9 units.