The correct option is C 16
The number of different types of gametes produced by a diploid organism can be calculated by formula 2n, where n is the number of heterozygous loci.
In the given case, the organism is heterozygous for 4 loci or in other words is heterozygous for 4 pairs of alleles.
Hence the number of different types of gametes produced by the organism would be 24=16.