This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Molecular Biology Techniques, Subject name: Biochemistry
[{'content': 'Purpose of gene therapy: \nSelect and explain. \nA. Replacement of abnormal gene by normal gene, B. Replacement of normal gene by abnormal gene, C. Knock out of abnormal gene, D. Introduction of viral gene', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. A. Replacement of abnormal gene by normal geneNovel area of therapeuticsIntracellular delivery of genes to generate a therapeutic effect by correcting an existing abnormalityDivided into1. Somatic cell gene therapy: Gene is introduced into somatic cells.2. Germ cell gene therapy (Transgenic animal)', 'role': 'assistant'}]