The flower color in a plant X is determined by a gene with two alleles, one for red flowers (R) and one for white flowers (r). When a pure breed having red-colored flowers is crossed with a pure breed of white-colored flowers, all the resulting offspring are pink-colored (F1), which upon self-fertilization gives a 1:2:1 phenotypic ratio of red: pink: white flowers in the F2 generation. From the above experiment, which of the following conclusions can be drawn?