Answer:
Commensalism, +/0
Step-by-step explanation:
Commensalism is an association between two organisms in which one benefits and the other is unaffected. In this relationship between the elephants and the cattle egrets, the elephants provide food (insects) for the cattle egrets by exposing them but the elephant itself is neither done any harm or benefit.
+ means positive effect on the organism, - means negative effect, and 0 means no effect. In this relationship,there is a positive effect on the cattle egrets (i.e +), and a neutral effect on the elephants (i.e. 0).
so the denotation will be +/0