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 defense.
(iii) The method involves silencing of specific mRNA using a complementary dsDNA molecule that binds and prevents the translation of mRNA.
(iv) using retrovirus vectors , nematode–specific genes were introduced into the host plant .