Neolithic farmers found that the soil along rivers was especially fertile because

a they slashed and burned the vegetation along rivers.

b annual flooding.

c they added fertilizers to the soil.

d animals deposited their manure more frequently along rivers.

Question

Neolithic farmers found that the soil along rivers was especially fertile because 

a they slashed and burned the vegetation along rivers.

b annual flooding.

c they added fertilizers to the soil.

d animals deposited their manure more   frequently along rivers.

anonymous · Answer

annual flooding replenished the land with a layer of topsoil