The genotype for the height of an organism is written as Tt. What conclusion may be drawn?

The allele for height has at least two different genes

There are at least two different alleles of the gene for height

There are two different genes for height each having a single allele

There is one allele for height with two different forms.

The genotype Tt represents two different alleles of the same gene:

This means the organism is heterozygous for the height gene — it has two different alleles (T and t) of one gene.