To solve this problem, we need to identify which type of ecosystem has plants arranged into well-defined vertical layers based on their height. Let's analyze each option:$\newline \bullet$Option 1: Tropical rain forest.$\newline$ - Tropical rain forests are known for their high biodiversity and complex structure.$\newline$ - They have distinct vertical layers, including the emergent layer, canopy, understory, and forest floor.$\newline$ - This vertical stratification is a key characteristic of tropical rain forests.$\newline \bullet$Option 2: Grassland.$\newline$ - Grasslands are dominated by grasses and have few trees or shrubs.$\newline$ - They do not exhibit well-defined vertical layers like forests.$\newline \bullet$Option 3: Temperate forest.$\newline$ - Temperate forests have some vertical stratification, but it is less pronounced than in tropical rain forests.$\newline \bullet$Option 4: Tropical Savannah.$\newline$ - Tropical savannahs are characterized by a mix of grasses and scattered trees.$\newline$ - They do not have the complex vertical layering seen in tropical rain forests.$\newline$Based on this analysis, the presence of well-defined vertical layers depending on plant height is best seen in tropical rain forests.$\newline$Therefore, the correct option is Option 1: Tropical rain forest.