The multiplicity of a factor in a polynomial refers to how many times that factor appears in the polynomial. A factor must have a non-negative integer multiplicity, which means it can be 1, 2, 3, etc., but it cannot be negative or a fraction.
Given that \( (2x + 3) \) is a factor of \( p(x) \), the only possible multiplicity from the options provided is:
1
So, the answer is 1.