During transcription process in eukaryotes, 'capping' involves:

Addition of methyl guanosine triphosphate to 5' - end of hnRNA.

The correct answer is Option (2) → Addition of methyl guanosine triphosphate to 5' - end of hnRNA.

In eukaryote,  Primary transcripts contain both the exons and the introns and are non-functional. Hence, it is subjected to a process called splicing where the introns are removed and exons are joined in a defined order. hnRNA undergoes additional processing called as capping and tailing. In capping an unusual nucleotide (methyl guanosine triphosphate) is added to the 5'-end of hnRNA. In tailing, adenylate residues (200-300) are added at 3'-end in a template independent manner. It is the fully processed hnRNA, now called mRNA, that is transported out of the nucleus for translation.