The correct option is B Pure line selection
Pure line is a self pollinated descendent of a self pollinated plant. It is is a method in which new variety is developed by selection of single best plant progeny among traditional varieties or land races.
Characteristics of pure line :
1. All plant within a pure line has same genotype as the plants from which the pure lines are cerived.
2. The phenotypic differences (variation) within a pure line is environmental and therefore non heritable.
3. The pure line becomes genetically variable with time, due to mechanical mixture, mutation, etc.
1. Superior line is used as variety.
2. It is used as parent in development of new variety by hybridization.
3. Pure lines are used for studying mutations and other biological investigations, such as medicine, immunology, physiology and biochemistry.