Question

Sarah is studying dominant alleles in snapdragons. She read the red flowers (R) are dominant, and non-red flowers are recessive (r). Later, while walking, she was a snapdragon must be recessive for flower color. What information did Sarah use to come to this conclusion?
A) the snapdragons phenotype
B) the snapdragons genotype
C) the snapdragons chromosomes
D) the snapdragons DNA