The polynomial x2y + 3xy2 + 1 is a with a degree of .

The degree of a multivariable polynomial is the greatest sum of exponents in any term. In x²y, the exponents add to 2 + 1 = 3, and in 3xy² they add to 1 + 2 = 3; the constant 1 has degree 0. Therefore, the polynomial has degree 3, so the correct choice is C, 3.

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