Match the type of population interaction with its description.
| Column I | Column II |
|---|---|
| (a) Mutualism | (i) One species benefits, the other is harmed (+, -) |
| (b) Competition | (ii) One species benefits, the other is unaffected (+, 0) |
| (c) Predation | (iii) Both interacting species benefit (+, +) |
| (d) Commensalism | (iv) Both interacting species are harmed (-, -) |