Which of the following interspecific interactions can be represented as ‘+ –’ depending on the outcome of the interaction to each species?

Ticks are ectoparasites on dogs. In this interaction, the host is the dog which is harmed (–); the parasite is the tick which is benefited (+).Orchid and mango tree - Commensalism (+ 0) Wasp and fig plant - mutualism (+ +)Balanus and Chthamalus - Competition ( - - )