The answer is commensalism.
The complete answer is: The ecological relationship between organisms where one benefits and the other is not affected is commensalism.
There are four kind of ecological relationships between two organisms: mutualism, amensalism, parasitism, commensalism.
In mutualism the two organisms benefit from each other.
In amensalism one organism in unnafected and the other is harmed.
In parasitism one organism is benefited ant the other harmed.
