Gregor Mendel crossed homozygous tall plants (TT) with homozygous short plants (tt). All the resulting offspring were tall. From these results, what conclusion did Mendel draw?

The conclusion he drew was that the allele for tall plant height was dominant to that of short plant height.

We are given with 2 genes homozygous tall plants (TT) with homozygous short plants (tt). The ensuing offspring are tall, which implies the dominant attribute is tallness. this can be true since the chance of various height like all are short or some are tall and short could also be doable. answer is a

allele for tall plant height was dominant

Explanation:

Gregor Johann Mendel, called the "father of recent biology," was born in European country in 1822. His experiments showed that the inheritance of bound traits in pea plants follows explicit patterns, later turning into the inspiration of recent biology and resulting in the study of heredity.