Two Genes ( a and B ) Are Located on Each

Two genes ( A and B ) are located on each of two pairs of homologous chromosomes. In a tetrad, one sister chromatid contains alleles ab , while the other sister chromatid contains alleles AB (upper and lower case indicate different alleles of the same gene) . Which genetic combinations are possible in the four gametes that are produced from a single chiasma between these chromosome pairs?

A) Ab , AB , ab , aB
B) Ab , Ab , aB , aB
C) Aa , Bb , ab , Ab
D) Ab , Ab , AB , AB
E) AB , AB , ab , ab