Apical meristems in the infected plants are generally either free or carry a very low concentration of the viruses. The various reasons attributed to the escape of the meristems by virus invasion are:
a) Viruses move readily in a plant body through the vascular system which in meristems is absent,
b) A high metabolite activity in the actively dividing meristematic cells does not allow virus replication and
c) A high endogenous auxin level in shoot apices may inhibit virus multiplication.
Therefore, the main objective of shoot-tip and meristem –tip culture is the production of disease-free plants through micropropagation.
Therefore, the correct answer is option D.