If a corn plant has a genotype sstt, what are the possible genetic combinations that could be present in a single grain of pollen produced by the plant?

Since pollen is a gamete, that means that it will get half of the genetic information required to make the corn plant. (Pollen is like sperm, that will find a stigma to then proceed to pollinate the flower and make a plant, after a few processes.) All possible genetic combinations in pollen would be... ST, St, sT, st. I used a punnett square to determine the possible combinations. And attached to this I have a poorly drawn sketch of what I did. I am new here so I don't know if you have a question ask me or something.