Step 1: Think in time order
List the four events by date: 1947, 1949, 1955 and 1961. A peak usually comes in the middle of a trend after early steps and before the trend weakens.
Step 2: Describe the trend
Between 1947 and 1955 India kept holding or joining Afro-Asian meetings. Each one drew in more countries. After 1955 the focus moved towards the non-aligned group, and the 1962 war with China hurt the Afro-Asian unity.
Step 3: Judge the early meetings
The 1947 Asian Relations Conference and the 1949 conference on Indonesia were smaller and about a few concerns. They set the base, but they did not bring in the full group of Asian and African states.
Step 4: Judge the Bandung meeting
Bandung in 1955 had delegates from 29 countries. It adopted principles of peaceful coexistence and cooperation. Nehru was a leading voice. This is the largest show of Afro-Asian unity.
Step 5: Judge the Belgrade summit
Belgrade in 1961 started the Non-Aligned Movement. It included countries from Europe and Latin America too, so it is not mainly an Afro-Asian event.
Step 6: Conclude
Bandung is the high point. The answer is option 3.
Final Answer:
Bandung 1955 is the zenith of India's Afro-Asian engagement.
\[ \boxed{\text{Option 3}} \]