The Haffkine Institute in Mumbai is renowned for its research and development in the field of vaccines. Although all options listed are vaccines for various diseases, the Haffkine Institute is specifically known for its work on the production of plague vaccine. Plague is a severe and highly contagious bacterial disease caused by the bacterium Yersinia pestis. Inoculation of plague vaccine can provide immunity against this deadly disease.

Option 2, leprosy vaccine, is incorrect as the Haffkine Institute does not specialize in the production of this vaccine. Leprosy, also known as Hansen`s disease, is caused by the bacteria Mycobacterium leprae and requires a different approach for prevention and treatment.

Option 3, tetanus vaccine, is also incorrect. Tetanus, caused by the bacterium Clostridium tetani, is preventable through vaccination. However, the Haffkine Institute does not focus on the production of tetanus vaccine.

Option 4, polio vaccine, is incorrect as well. Polio, caused by the poliovirus, is another vaccine-preventable disease, but the Haffkine Institute does not specialize in the production of polio vaccine.

Therefore, the correct answer is option