Transfer relationship refers to any element A, B, C, if element A has a certain relationship with element B and element B has this relationship with element C, then element A and element C also have this relationship. Reverse transfer relationship refers to if element A has a certain relationship with element B and element B has this relationship with element C, but element A and element C have no such relationship.
According to the above definition, which of the following relationships is transfer relationship?
The natural enemy relationship of the food chain.