The correct answer is option 4, Dr Zakir Hussain. Dr Zakir Hussain had the shortest tenure as the President of India. However, it is worth noting that his short tenure was not due to any fault or issue during his presidency. Dr Zakir Hussain served as the President of India from May 13, 1967, until his untimely death on May 3, 1969. He passed away while still in office, which resulted in his tenure being cut short. It is unfortunate that he did not have the opportunity to serve a full term as the President of India. Nonetheless, his contributions during his tenure were significant and he is remembered as a respected and influential figure in Indian politics.