A Testcross of Trihybrid Drosophila Produced the Following Phenotypes and Number

Multiple Choice

A testcross of trihybrid Drosophila produced the following phenotypes and number of offspring. A table showing phenotype and the number of offspring with each phenotype is below. A plus sign is used for wild-type phenotype; a letter indicates the mutant phenotype for that gene. $\begin{array} { l r } + + + & 669 \\a b c & 653 \\+ + c & 121 \\a b + & 139 \\+ b + & 2280 \\a + c & 2215 \\+ b c & 3 \\a + + & 2\end{array}$
-The cross represented by a^+b+c+/abc × abc/abc is

A) a two-point testcross.
B) a three-point testcross.
C) a parental cross.
D) a haploid cross.
E) None of these