4. if one individual is tt and another individual is tt, which of the following is true?
the two have different genotypes and the same phenotype.
the two have the same genotype and the same phenotype.
the two have different genotypes and different phenotypes
the two have the same genotype and different phenotypes.

Tt is a genotype different than tt. The first one has two different alleles (T and t) the second one has one kind of alleles (t).

The fenotype of Tt is given by the dominant character (which is the capitalized one, T) while the fenotype of tt is t (because it is the only one).

Then, there are two different genotypes and two differente phenotypes.

The two have different genotypes and different phenotypes.