If all of the sex cells (gametes) an organism has the t allele genotype, then the organism itself must have a tt genotype.

Here's why:

* Sex cells are haploid: They contain only one copy of each chromosome.

* Organisms are diploid: They have two copies of each chromosome, one from each parent.

* During meiosis: The process that produces sex cells, the two copies of each chromosome are separated, so each sex cell receives only one copy.

Therefore, if all the sex cells have the t allele, it means that the organism must have contributed the t allele from both chromosomes. This leads to a tt genotype for the organism.