In a chromosome, there is a specific DNA sequence, responsible for initiating replication. It is called as:

Option (4) is the correct answer because origin of replication (ori) is a sequence from where replication starts and any piece of DNA when linked to this sequence can be made to replicate, within the host cells. Option (1) is incorrect because recognition sequence is a specific palindromic nucleotide sequence in DNA recognised by restriction endonuclease. Options (2) and (3) are not the answers because cloning site/restriction site is the site on the vector for the use of restriction enzyme and it is similar to recognition site.