Which of the following statements are correct regarding the process of RNA interference?
(i) RNAi has been used to prevent nematode infestation of tobacco plants.
(ii) RNAi takes place in all eukaryotic organisms as a method of cellular defence.
(iii) The method involves silencing of specific nRNA using complementary dsDNA molecule that binds and prevents translation of mRNA.
(iv) Using retrovirus vectors, nematode-specific genes were introduced into the host plant.