A variety of pea plant called Blue Persian produces a tall plant with blue seeds. A second variety of pea plant called Spanish Dwarf produces a short plant with white seed. The two varieties are crossed, and the resulting seeds are collected. All of the seeds are white; and when planted, they produce all tall plants. These tall F₁ plants are allowed to self-fertilize. The results for seed color and plant stature in the F₂ generation are as follows:
     F₂ Plant Phenotype        Number
     Blue seed, tall plant.          97
     White seed, tall plant        270
     Blue seed, short plant        33
     White seed, short plant     100
    TOTAL                                500

State the hypothesis being tested in this experiment.