Proper sequence of question-:
The correct order is
a--> ds RNA binds and prevents translation of the mRNA.
b-->using Agrobacterium as vector introduce it into tobacco
c-->this produce both sense and antisense RNA in the host cells.
d--> These two RNAs are complementary to each other and form a double stranded RNA
e--> initiates-RNA interference
f--> it silences the specific mRNA of the nematode
g--> The parasite cannot survive in transgenic host
h--> so the plant is prevented from pest