Answer:
"T" X "t" yields offspring that are all heterozygous with genotype "Tt"
Explanation:
An Allele refers to either of a pair of contrasting genes.
So, "TT" being the same yeild just one allele (T), while "tt" also yield one allele (t)
So, the cross of the both alleles
"T" X "t"
yields offspring that are all heterozygous with genotype "Tt"
Thus, the crossing dominant tall plant height "TT" and recessive short plant height "tt" yielded heterozygous tall plants "Tt"