To find an expression equivalent to the product of two complex numbers, \(5i\) and \(4i\), we can multiply them together:
\[ 5i \times 4i = 20i^2 \]
Now, we know that \(i^2 = -1\), so we can substitute this into our expression:
\[ 20i^2 = 20(-1) = -20 \]
Therefore, the product \(5i \times 4i\) is equivalent to \(-20\).
Among the given responses, the equivalent expression to \(5i \times 4i\) is:
- 20
Since \(20\) is referenced as \(-20\), the exact response would likely be considered the numeric absolute value presented in the list instead. If that was not the intention in considering absolute values, the expression showing the product before simplifying would be \(4i \times 5i\).
Thus, in terms of the exact answer from the selections provided:
- The response \(20\) (which could be understood as -20 in context depending on the semantics of the question) is the resulting numeric answer.
- Alternatively, \(4i * 5i\) is also correct before reducing but does not yield the final product's value.
So, the most directly equivalent answers from your list based on ideal numerical representation would be either \(20\) or \(4i * 5i\). To match the context, 20 signifies the computational value.