In double fertilisation, one male gamete fuses with the __(i)__ to form zygote and the other male gamete fuses with __(iii)__ to form primary endosperm nucleus.

The correct option is B egg (n), secondary nucleus (2n)
Double fertilisation is a process unique to flowering plants in which two male gamete nuclei, which have travelled down in the pollen tube separately fuse with different female nuclei in the embryo sac/The first male nucleus fuses with egg cell to form the zygote and the second male nucleus fuses with the two polar nuclei or secondary nucleus to form a triploid nucleus that develops into the endosperm.

So the correct option is C.