When I cut open a tomato only to find one seed. What most likely kept that tomato from forming more seeds?

The presence of only one seed in a tomato can result from several factors, including genetic mutations, environmental stressors, or improper pollination. Insufficient pollination may occur if the flower did not receive enough pollen, leading to incomplete fertilization. Additionally, factors like nutrient deficiencies, temperature extremes, or water stress during the growing season can also affect seed development. Ultimately, these conditions can hinder the fruit's ability to develop multiple seeds.