Answer:
Mutualism
Step-by-step explanation:
The ostrich and gazelle have a mutualistic relationship. They help each other in terms of predator detection. Ostriches are tall and this enables them to see predators from afar, and they also have good eyesight. However, their sense of hearing and smell are not too good. This is where the gazelles come in.
Gazelles are short and they do not have the same advatageous vantage point of the ostriches, but they have better senses in terms of hearing and smelling. When each of them observe that the other is wary, they know that there is a predator around.