Question $3(2\mathrm{.}5$ points$)$

In pea plants, tall $(T)$ is dominant to short $($ t $).$ If you had a tall pea plant of unknown genotype $($T$\_),$ what would be the best cross to do that would show you the tall plant's genotype $($TT or Tt$)?$

None of these would be useful

A heterozygous tall plant $($Tt$)$ because if all the offspring are tall, then all the offspring will be Tt $,$ whereas otherwise there would be a $50\%$ to $50\%$ ratio of tall to short plants.

A homozygous tall plant $($TT$)$ because if all the offspring are tall, then all the offspring will be TT$,$ whereas otherwise there would be a $75\%$ to $25\%$ ratio of tall to short plants.

A homozygous short plant $($ tt $)$ because if the tall plant is TT then all offspring will be Tt $,$ whereas if the tall plant is Tt $,$ then $50\%$ of the offspring will be tall and $50\%$ short.