1. The sentence discusses the Game Boy becoming popular worldwide. 2. 'popular' is an adjective describing the Game Boy. 3. 'more popular' or 'most popular' would fit, but 'more popular' is often used for comparison or general increase. However, considering the context of becoming one of the most popular items, 'most popular' is a stronger fit. Let's re-evaluate. The sentence states 'It became one of the D all over the world.' This implies a superlative. 4. 'most popular' fits the superlative context.
most popular