Let us define the term,
The degree of a polynomial is the highest of the degrees of the polynomial's monomials (individual terms) with non-zero coefficients.
Let us write out the given expression,
![2x^2+3x+1](https://img.qammunity.org/2023/formulas/mathematics/college/vh47tkvrnrkd9uwn6n0pqhnk29h20gnf6m.png)
From the given equation, the highest degree of the polynomial is 2.
Hence, option D is the correct answer.