In corn, the genes for tassel length (alleles T and t) and rust resistance (alleles R and r) are known to be on separate chromosomes. In the course of making routine crosses, a breeder noticed that one T / T ; R / r plant gave unusual results in a testcross with the double-recessive pollenparent t / t ; r / r. The results were

Progeny:
T / t ; R / r 98
t / t ; r / r 104
T / t ; r / r 3
t / t ; R / r 5

Corn cobs:Only about half as many seeds as usual

a. What key features of the data are different from the expected results?
b. State a concise hypothesis that explains the results.
c. Show genotypes of parents and progeny.