How many types of gametes are produced in the $F_1$ generation of a trihybrid cross?

In a dihybrid Mendelian cross,how many types of genotype and phenotype will be obtained $:-$

Which genotype represents a true dihybrid condition?

In a typical Mendelian dihybrid cross,one parent is homozygous for both dominant traits and another parent is homozygous for both recessive traits. In the $F_2$ generation,both parental combinations and recombinations appear. The phenotypic ratio of parental combinations to recombinations is

In Mendel's dihybrid cross,what is the probability of obtaining a homozygous recessive plant in the $F_2$ generation?

The genotypes of a plant variety were $TtHh, Tthh, ttHh$ and $tthh$,where $T =$ tallness and $H =$ hairy stem. Which one of the following crosses would produce progeny giving a phenotypic ratio approximately $1 : 1 : 1 : 1$?