The answers are; B & C
Leakage of the lagoon will cause the contaminants to seep through the soil to the groundwater. The plume will diffuse and spread over a large area including affecting the quality of the water in springs and wells.
If severe weather causes flooding of the lagoon, the contaminants may runoff into low lying areas affecting the composition of the soils. The sudden imbalance will cause a particular population to die while giving opportunities for others to rise. This is how ecosystem are affected just like algae blooms in water bodies.