The correct answer is Option (2) –In capping

Methyl guanosine triphosphate is added to the 5’ end of hnRNA (pre-mRNA) during the process known as capping.

hnRNA undergoes additional processing called as capping and tailing. Capping is a post-transcriptional modification that occurs in eukaryotic mRNA processing. 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.

Therefore, the correct process where methyl guanosine triphosphate is added to the 5’ end of hnRNA is during capping.