Let's first calculate the area of the original rectangle.
The area of a rectangle is given by the product of its length and width. In this case, the length of the rectangle is 14 cm, and the width is 10 cm. So, the area of the rectangle is 14 cm * 10 cm = 140 square cm.
Now, let's calculate the size of the side of the square (which we'll call 's'). Because the original rectangle was turned into a square, the length of the rectangle was reduced by x cm and its width was increased by x cm. Thus, the side of the square is 14 cm - x cm, which should be equal to 10 cm + x cm.
In our case, by setting these two expressions equal to each other and solving for x, we can determine that x = 2 cm.
So, the length of the side 's' of the square turns out to be 14 cm - 2 cm = 12 cm.
The area 'AS' of a square is calculated as s^2 = (12cm)^2 = 144 square cm.
Finally, let's calculate the change in the area.
The change in area ΔA = AS - AR = 144 square cm - 140 square cm = 4 square cm.
Thus, The change in the rectangle's area as it was transformed into a square is 4 square cm. So, the correct answer is not listed among the options given. There must be some mistake in the options provided.