Although the gateway concept is still being debated, there is little disagreement that serious drug users begin their involvement with:

alcohol

Explanation:

Based on the information provided within the question it can be said that there is  little disagreement that serious drug users begin their involvement with alcohol. This is why alcohol is considered the king of gateway drugs. Since it is a vice that is legal and provides a "buzz" for potential drug users to get started.

answer: grassland biomes are closer to the equator and receive more rain.

grasslands are biomes that are dominated by grasses rather shrubs and trees. savanna are biomes that exhibit grasses, shrubs and small tree as vegetation. grasslands are located near the equator of the earth. these are found in north america. savanna biomes are found in africa, south america, australia and india. grassland exhibit moderate climatic conditions, it receives   amount of rainfall higher than savanna.   therefore, savanna exhibit dry and hot climatic conditions.