The correct answer is sex linkage.
Sex linkage refers to the phenotypic expression of an allele, which relies upon the gender of an individual and is directly associated with the sex chromosomes. These genes are regarded sex-linked as their expression and patterns of inheritance vary between the males and females. The sex linkage cannot be the same as genetic linkage, the sex-linked genes can be associated genetically.
Punnet square
Pink flower x pink flower
rw rw
F1 generation
rr, rw, rw, ww
Probability
red flower (rr) = 1
pink flower (rw) = 2
wite flower (ww) = 1
The answer is A, a cell wall