Isn't the nucleus the largest one? Why is there only one option with nucleus first and it's not in the right order?

In sweet pea, gene c is responsible for color production and gene p is responsible for the purple color pigment. both of them are located on two different loci on different chromosomes. the flowers will be purple only when the plant has the genotypes as c_p_. no color will be produced with genotypes: ccpp, ccpp, ccpp, ccpp. thus, gene c controls the expression of gene p. what pattern of inheritance is exhibited here? a. pleiotropy b. epistasis c. multiple alleles

Plz ! what does it mean for an allele to be dominant?

The smallest parts of these that retain their original properties are called