A heterozygous organism for 4 gene pair AaBbCc was test crossed to the homozygous recessive parent and 1000 progenies were obtained with the following genotypes: aBCD (42), Abcd (43), ABCd (140), abcD (145), aBcD (6), AbCd (9), ABcd (305) and abCD (310). Which gene pairs are linked, recombinants and parental types? give reasons for the answers