Plant breeding is defined as:

Plant breeding is indeed defined as the science of changing the traits of plants for desired characteristics. This process involves selective breeding, genetic modification, and various biotechnological techniques aimed at enhancing yield, disease resistance, nutritional value, and environmental adaptability of crops. By utilizing genetics and plant biology, breeders can identify specific traits to either introduce or enhance in plant populations.

The focus of plant breeding is on achieving specific objectives that address agricultural challenges, leading to improved crop varieties that can better meet human food needs or withstand environmental stresses. This definition encapsulates both traditional methods of breeding as well as modern biotechnological approaches that have been developed to accelerate the breeding process and enhance traits more effectively.

Other choices do not encompass the full scope of plant breeding. Improving soil nutrients relates to agronomy rather than the breeding of plants. Limiting plant breeding to only traditional farming techniques disregards the advancements made through biotechnology. Lastly, while managing crop pests is a critical part of agricultural practices, it does not define plant breeding itself, as plant breeding focuses on the characteristics of the plants rather than directly controlling pests.