The correct option is A Ribosome
Replication of DNA copies the genetic information present in it which is transcribed into RNA by RNA polymerase enzyme. Both DNA replication and RNA transcription takes place in nucleus only. The RNA sequence of ribonucleotides is translated into amino acid sequence of polypeptides by process of translation. The process of protein synthesis occurs on ribosomes in cytoplasm. Therefore, DNA sequence is conserved in amino acid sequence of proteins on ribosomes. Since, ribosomes are the site of protein synthesis, correct answer is A.