The correct answer is: D. Cannot be determined from the given information.
The number of degrees of freedom in a goodness of fit test is the number of categories minus the number of parameters estimated. In this case, we are told that there are 8 possible classes under consideration, but we are not told how many parameters are estimated. Therefore, the number of degrees of freedom cannot be determined.
To illustrate, consider the following two examples. In the first example, we have 8 possible classes and we estimate 1 parameter. In this case, the number of degrees of freedom would be $8-1=7$. In the second example, we have 8 possible classes and we estimate 2 parameters. In this case, the number of degrees of freedom would be $8-2=6$.
Therefore, the number of degrees of freedom in a goodness of fit test depends on both the number of categories and the number of parameters estimated. Without knowing both of these pieces of information, the number of degrees of freedom cannot be determined.