Answer:
Soil erosion causes siltation in rivers, dams, etc. In some areas, huge river deltas are formed (such as River Nile delta) because of soil erosion. Such places are good for agriculture but not good for urbanization. However, some people do not care about it, they just want to construct buildings on alluvium type soils.
Answer:
C
Explanation:
Becuase fom a vaccine you are recieving antibodies by another animal or human donor.
D is unlinkely since it describes how the mother is nursing the baby, so nothing directly mentioning of the baby recieving any antibodies. The other options also talk about how the body creates its own antibodies, which isn't passive immunity.
Water is the single source as it provides the electrons by splitting into oxygen and hydrogen. This process happens during the light-dependent reactions.
The correct answer is A.
I hope I've helped!