The correct characterization for the algebraic expression -7 is: leading coefficient: -7; constant term: -7; degree: 0. It is a constant term with no variable factors, hence not a polynomial. Option B is correct.
The algebraic expression -7 has a leading coefficient of -7, a constant term of -7, and a degree of 0. It is a monomial, a specific case of a polynomial with no variable factors. The leading coefficient is the coefficient of the highest-degree term, and in this case, there are no variable terms, resulting in a degree of 0.
The expression represents a constant value, and it is classified as a polynomial with a single term. Therefore, the correct characterization is that of a monomial with a leading coefficient of -7, a constant term of -7, and a degree of 0. The correct answer is option B.