Step 1: The sentence talks about Jawaharlal spending his childhood at a specific place, Anand Bhawan.
Step 2: When we refer to a particular building or house as a point of residence, we normally use the preposition at.
Step 3: In is used for larger enclosed areas like a city, country, or room, not for a named house treated as a point.
Step 4: On is used for surfaces or specific days, and Across means from one side to the other, neither of which fits here.
Step 5: So the sentence reads: Jawaharlal spent his childhood at Anand Bhawan.
Answer: option 1, At.