If you buy two plants of the same species that have the same-colored flowers, they must have different genotypes.

False

Explanation:

They are displaying the same phenotype. That doesnt mean they have the same genotype.

For example lets say the plants colours are purple (P)

one plant may have the geneotype of PP, (two dominant purple coloured alleles), the other plant may have the genotype Pp, (one dominant purple allele and one recessive allele for another colour lets say pink). Because purple (P) is the dominant allele they are both the same colour displayed but they have different genotypes.

c is the answer : )               your welcome