Answer : 3. "15 अगस्त 1969"
Explanation :

The Indian Space Research Organisation (ISRO) was founded on August 15, 1969. It was established by Dr. Vikram Sarabhai, who is often regarded as the father of the Indian space program. ISRO has played a crucial role in the development of space technology in India and has achieved numerous milestones in space exploration and satellite launches.