Concept:Citrus is a perennial fruit crop that is commonly multiplied by budding to preserve desirable traits.Explanation:Citrus varieties do not grow true from seeds.Stem cuttings and layering are less reliable for large-scale commercial propagation.Budding, especially shield or T-budding, is the standard method used for citrus.It produces strong, disease-resistant rootstocks and ensures uniform fruit quality.Answer:A. budding