Q. Which of the following pairs are correctly matched?

1. Thomas Hunt Morgan – Chromosomal theory of inheritance (Drosophila)
2. Edward Jenner – Smallpox vaccine
3. Karl Landsteiner – Blood group classification
4. Jean-Baptiste Lamarck – Chemotherapy with arsenic compounds

Select the correct option from the codes given below:
Answer: 1, 2, and 3 only
Notes: Thomas Hunt Morgan demonstrated chromosomal inheritance using Drosophila. Edward Jenner developed the smallpox vaccine. Karl Landsteiner discovered the ABO blood group system. Jean-Baptiste Lamarck proposed inheritance of acquired characteristics; chemotherapy with arsenic compounds was developed by Paul Ehrlich, not Lamarck. Therefore, only statements 1, 2, and 3 are correct.