The genotype of an organism is the combination of alleles it has at a particular locus. In contrast, the phenotype is the observable characteristics that are produced by the genotype.
B and D are phenotypes, and are therefore not possible genotypes.
In a cross between tt ff and TT FF, the only alleles that tt ff can pass on are t/f, and the only alleles TT FF can pass on are T/F. Therefore, the only possible genotype is Tt Ff
