Final answer:
The correct length of the rectangle is given by the expression -|6| + 4, which simplifies to 4, since the absolute value of -6 is 6 and subtracting it from itself yields 0.
Step-by-step explanation:
The expression that correctly gives the length of the rectangle is -|6| + 4. The absolute value of -6 is 6, so |-6| equals 6. Therefore, when we subtract |6| from itself, we get 0. Adding 4 to 0 gives us the length of 4, which is the correct answer. It's important to note that absolute value denotes the distance from zero, so it is always non-negative. As for expressions like |-6| - 4, they would imply the rectangle has a negative length, which is not possible in geometry.