The correct option is A Young pollen grain
The basic principle of anther or pollen culture is the production of haploid plants exploiting the totipotency of micro spore and the occurrence of single set of chromosome (n) in the micro spore. In this process, normal development and the function of pollen cell to become a male gamete is stopped and is diverted forcefully to a new metabolic pathway for vegetative cell division. The principle behind anther culture is that, without disturbing the natural habitat and environment of the enclosed anther, pollen can be grown by culturing the intact anther.