Which events are likely to be catastrophic to an ecosystem? (select three correct answers) a. a volcanic eruption b. an oil spill c. leaves changing color in the fall d. the average annual melting of snow e. the introduction of a species that reproduces quickly

The following events will be catastrophic to an ecosystem:
1. Al volcanic eruption
2. An oil spill  and 
3. The introduction of a species that reproduce quickly.

A volcanic eruption will disrupt both the plants and the animal activities in a particular ecosystem and lead to loss of habitation. Depending on the extent of the volcanic eruption, a whole ecosystem can be completely wipe out. An oil spill is very poisonous to aquatic ecosystem and it leads to the death of the organisms that live in the water. Introducing a specie that reproduce quickly into an ecosystem will lead to fast taking over of the ecosystem by that specie to the detriment of other species. 

Abay where the river empties into the sea

What do you mean about innate behavior i don’t get it