A Dihybrid AaBb Female Drosophila Is Testcrossed with an Aabb $\quad$

A dihybrid AaBb female Drosophila is testcrossed with an aabb male.The following offspring genotypes were obtained.
AaBb $\quad$ 99
Aabb $\quad$ 83
AaBb $\quad$ 86
Aabb $\quad$ 92
A $\chi$ ² test was performed to determine whether the data supported the original hypothesis that the genes are unlinked.How many degrees of freedom should be used in this analysis?

A) 1
B) 2
C) 3
D) 4
E) 5