In a monohybrid cross between pure tall pea plant with pure dwarf...

A pure tall pea plant has the genotype $TT$ and a pure dwarf pea plant has the genotype $tt$.

The cross between them (TT \times tt$) produces$F_1$offspring with the genotype$Tt$(heterozygous tall).<br><br>Selfing the$F_1$generation (Tt \times Tt$) yields the $F_2$ generation.

The genotypes produced in the $F_2$ generation are $TT$, $Tt$, and $tt$.

Thus, there are $3$ types of genotypes found in the $F_2$ generation.

Answer: 3