Why did the first inhabitants of mainland Southeast Asia settle in plains and river valleys?
Those areas were easy to defend
Those areas were good for farming
Those areas were best for trade
D. Those areas were close to towns
The correct answer is B. Those areas were good for farming.
The first inhabitants of mainland Southeast Asia settled in plains and river valleys because these areas had fertile soil and access to water sources, which made them ideal for agricultural activities. The availability of fertile land and water for irrigation allowed them to cultivate crops and establish settled farming communities.