A hybrid with desirable traits is obtained by

The correct options are
A cross-hybridisation of pure lines
B cross-pollination of selected parents
Pure lines created by self-pollination are used as parents to create hybrids. Cross-pollination or cross hybridisation of two selected pure line parents leads to the formation of the desired progeny. This F1 hybrid is thus superior to both of its parents, and this tendency of it is called hybrid vigour or heterosis.