Each trait of a plant is determined by

an allele

one gene

Ca pair of genes

one dominant gene

Answer: a pair of genes

Explanation: Basically, most traits in living organisms both plants are animals are controlled by a pair of gene. This is because for each trait, one gene is inherited from the mother and one gene from the father, making it a pair of gene. The pair of gene inherited can either be in a homozygous (when the two alleles that formed the pair are identical) or in a heterozygous (when the two alleles are not identical) fashion. Examples of a homozygous inheritance is SS, RR, aa, tt. Examples of heterozygous inheritance is Bb, Tt, Rr, Aa.

A homozygous inheritance involves two copies of either a dominant or a recessive allele, while a heterozygous inheritance involves one copy of a dominant allele and one copy of a recessive allele.

An allele

I am not sure