How Are the Degrees of Freedom Calculated for a Chi-Square $\times$

Multiple Choice

How are the degrees of freedom calculated for a chi-square test?

A) (r - 1) / (c - 1)
B) (r - 1) (c -1)
C) (r $\times$ 2) - (c $\times$ 2)
D) (r + 1) - (c + 1)