The correct option is D Shoot apex culture
In tissue culture cells, tissues, and organs of a plant are separated. These separated cells are grown especially in containers with a nutrient media under controlled conditions of temperature and light. When the apex of shoot is used for multiplication by tissue culture, we get disease free plants because the shoot apical meristem, a group of dividing cells at the tip of a stem or root, is free from pathogens. Plants grown from tissue culture usually pass trough callus phase and show many variations. These show some agronomic characteristics like tolerance to pests, diseases, etc.