In which of the following interactions both partners are adversely affected?

The following graph depicts changes in two populations (A and B) of herbivores in a grassy field. A possible reason for these changes is that:

1.	both plant populations in this habitat decreased
2.	population-B competed more successfully for food than population-A
3.	population-A produced more offspring than population-B
4.	population-A consumed the members of population-B

According to Darwin, organic evolution is due to:

A high density of elephant population in an area can result in:

1. mutualism

2. Intraspecific competition

3. Interspecific completion

4. Predation on one another