Option 1, Dr. Sarvepalli Radhakrishnan, was the first Vice President of India and the second President of India. However, he was not the Secretary General of the Non-Aligned Movement.
Option 2, Varahagiri Venkatagiri, served as the fourth President of India but didn`t occupy the position of the Secretary General of the Non-Aligned Movement.
Option 3, Giani Zail Singh, is the correct answer. He served as the seventh President of India and also held the position of the Secretary General of the Non-Aligned Movement for some period of time.
Option 4, Dr. Shanker Dayal Sharma, was the ninth President of India but he was never the Secretary General of the Non-Aligned Movement. Thus, he is not the answer to this question.
In conclusion, Giani Zail Singh is the only Indian President among the given options who served as the Secretary General of the Non-Aligned Movement.