Answer:
C) It is one-half the area of a rectangle of length 4 units and width 5 units.
The total area of the triangle is 10, which we get by multiplying the height (5) times the base (4), which will be 20, and then dividing by 2, which is 10!
Given this information, we can start eliminating answers.
A) It is twice the area of a rectangle of length 4 units and width 5 units. This is answer is wrong, as the area of a rectangle with a length of 4, and a width of 5, is 20. Meaning that in order for this to be true, the area of the rectangle must be 40, which it is not.
B) It is one-half the area of a rectangle of length 4 units and width 5 units.
This is answer is right, as the area of a rectangle with a length of 4, and a width of 5, is 20, and half of that would be 10, which is half of the area of the triangle!
C) It is twice the area of a square of side length 5 units.
This answer is also wrong because the area of a square with side lengths of 5 would be 25, which is not half of the area of the triangle. In order for this to be true, the area of the rectangle must be 50, which it is not.
D) It is one-half the area of a square of side length 5 units.
This answer is wrong because the area of a square with side lengths of 5, would be 25, which is not twice the the area of the triangle. In order for this to be true, the area of the rectangle must be 12.5, which it is not.