A Dihybrid Testcross Is Made to Determine If Genes C

Multiple Choice

A dihybrid testcross is made to determine if genes C and D are linked.The results are shown in the table.
$\begin{array}{|l|c|r|}\hline \text { Parent genotypes: } & C c  D d \times c c d d & \\\hline & C c  D d & 222 \\\hline & C c  d d & 280 \\\hline \text { Progeny genotypes: } & c c  D d & 280 \\\hline & c c  d d & 218 \\\hline & & 1000 \\\hline\end{array}$
-Using the chi-square test for goodness of fit, how many degrees of freedom are in this data set?

A) 1
B) 2
C) 3
D) 4