Answer
The given expression is a polynomial of degree $0.$
Work Step by Step
A monomial is an expression of the form $ax^{k}$,
where $x$ is the variable,
the exponent $k$, a nonnegative integer, is the degree,
and $a$ is the coefficient of the term.
A polynomial expression is either a single monomial or a SUM of several monomials.
The degree of the polynomial is the degree of the monomial with the highest degree.
The given expression is a single monomial as it can be written as $5x^{0}$, with a degree of $0$.
Thus, the given expression is a polynomial of degree $0.$
