Answer:
The correct answer would be C) All offspring with at least one R will have red flowers.
The law of dominance states that the offsprings with heterozygous genotype will have the dominant trait in their phenotype, that is, only one copy of dominant allele is enough to produce the dominant trait in the phenotype.
Similarly, the offspring with at least one R (dominant allele) will have red flowers (dominant trait).
For example, the offspring produced by the cross of Rr and Rr would have three possible types of genotype; RR, Rr, and rr.
The offspring with RR and Rr will have red flowers due to the law of dominance while those with rr will have white flowers (recessive trait).