Flagellar phase variation occurs in salmonella and involves several genes and dna sites. several different mutations were made in those genes/sites to determine the effects on phase variation. for each mutation listed below, which flagellin is synthesized when the invertible region is in the position indicated? note: a null mutation results in the production of a nonfunctional product or no product at all. assume base changes result in inactivation of that site so it can no longer function. a nonpolar mutation does not affect expression of downstream genes in an operon. fljb flic both fljb and flic neither fljb nor flic a. a null mutation in the hin gene with the invertible region in the on position. b. mutations in the recombinase recognition sites in the recombination sites flanking the invertible region, with the invertible region in the off position. c. a polar null mutation in fljb with the invertible region in the off position. d. a null mutation in flja with the invertible region in the off position.