To demonstrate that 7 is a Mersenne prime, Ogechi should use the expression related to the definition of a Mersenne prime. A Mersenne prime is of the form \( 2^p - 1 \), where \( p \) is a prime number.
In this case:
- For \( p = 3 \), the expression \( 2^3 - 1 \) evaluates to \( 8 - 1 = 7 \).
So the correct expression to show that 7 is a Mersenne prime would be:
\[ 2^3 - 1 \]
Among the responses you provided, none of them clearly match the expression \( 2^3 - 1 \). However, if we assume the intention was to articulate the concept clearly, she could use the concept of \( 2^p - 1 = 7 \) to support her demonstration.
If the options contained \( 2^3 - 1 \), that would be the correct choice to use to demonstrate that 7 is indeed a Mersenne prime. If you need clarification or a specific choice from those options, please list them again!