The multiplicity of a factor in a polynomial function must be a non-negative integer. This means the possible values for the multiplicity of the factor (2x + 3) can be 1, 2, 3, etc.
From the options given, the valid multiplicities are:
- 1
- 2
The values 1.5 and -1.5 are not valid multiplicities for a polynomial's factor.
So, the possible multiplicities for the factor (2x + 3) could be 1 or 2.