To represent \(-3 \cdot 8\) using a model, we need to show that we are taking negative groups of 8 three times.
The correct representation from the given options is:
\[-(8 + 8 + 8)\]
This shows \(-3 \cdot 8\) as the negative of the sum of three groups of 8.
In more detail, \(-3 \cdot 8\) equals \(-24\), which can be seen as taking three groups of negative 8, which is represented as \(- (8 + 8 + 8)\).
So the final answer is:
−(8 + 8 + 8)