Answer:
b. incomplete dominance
Explanation:
Incomplete dominance is a type of inheritance that does not confirm to Mendel's principles of inheritance i.e it is non-mendelian. Incomplete dominance occurs when an allele of a gene does not completely mask the expression of another allele of the same gene, hence, the two alleles combine to form a heterozygous that is different but intermediate of both parent phenotypes.
This is the case in this question where the red allele (R) of a four o'clock plant is INCOMPLETELY DOMINANT over the white allele (W), hence, they both produce an intermediate pink phenotype (RW), which is a blending of both red and white phenotypes.
