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.
Winds are light at the equator because of the weak horizontal pressure gradients located there. The warm surface conditions result in locally low pressure. ... At this latitude surface high pressure causes the air near the ground to diverge.