In this question, the ant has 4 pairs of chromosomes. Each pair of chromosomes will be separated in a gamete, resulting 4 unpaired chromosomes. That is why gamete is called haploid or n.
That means only 1 of the 2 chromosomes that will be carried into a gamete, assuming the gene heterozygote then there would be 2 possibilities. Since each chromosome pairs can produce 2 possibilities for each male or female, their interaction will result as (2x2) 4 possibilities.
Then for 4 chromosomes would be 4^4 possibilities= 256 possibilities of offspring