The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
Replication is the process of formation of daughter DNA molecules by DNA polymerase enzyme using the existing DNA strands as a template. Transcription is the process of RNA synthesis using DNA template strand which is carried out by RNA polymerase; any one of two DNA strands can serve as a template. Since DNA and the enzymatic machinery for replication and transcription are present in the nucleus, the processes of replication and transcription occur in the nucleus only. The primary transcript, formed by the process of transcription, is then modified via post-transcriptional modifications into mature mRNA which is then transported to cytoplasm through nuclear pores where ribosomes (the site for protein synthesis) and amino acids (monomer for protein synthesis present in amino acid pool of cytoplasm) are present to carry out the process of translation i.e. synthesis of polypeptides by polymerization of amino acids on ribosomes using the mRNA triplets as template. Thus, the correct answer is option A.