This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
Gene therapy methods are: 
Select and explain. 
A. Electroporation, B. Intranuclear injection, C. Site directed mutagenesis, D. All
D: All
Answer: D: All 
Explanation: A i.e. Electroporation, B i.e. Intranuclear infection, C i.e. Site directed mutagenesis