Explanation

Let’s analyze each option under the assumption that a and b are integers:

a⁷ → Square of an integer → Always an integer

b* → Ambiguous; if it means b raised to some power (like a^b or b^a), then:

If b = 2 and a = -1, then b^a = 2⁻¹ = 0.5, not an integer

So, this is not necessarily an integer

a * b → Product of two integers → Always an integer

2a – 5b → Linear combination of integers → Always an integer