The correct options are
A Tsunami
B Excessive rainfall
C Overflowing of river
Tsunami, excessive rainfall and overflowing of river causes increase in water level of an area which can result in flood.
Soil erosion is the washing or blowing away (by water or wind) of the top layer of soil. This cannot be a direct cause of the flood. However, soil erosion may cause loss of vegetation. This can cause the chance of increased water level in a region, but still unlikely to cause flood.