Which of the following statements are correct?1. PCR is now routinely used to detect HIV in suspected AIDS patients.2. A single-stranded DNA or RNA tagged with a radioactive molecule (probe) is allowed to hybridize to its complementary DNA in a clone of cells followed by detection using autoradiography.3. ELISA is based on the principle of antigen-antibody interaction.4. Today transgenic models exist for many human diseases such as cancer, cystic fibrosis, rheumatoid arthritis, and Alzheimer’s.