This is a mutualistic relationship between the bee and flower. It is considered mutualism because the bee gets food and the flowers get pollinated so both benefit.
This is a parasitic relationship between a dog and flea. It is considered parasitism because on is harmed and one is benefited, the flea gets a home in a dogs fur and makes the dog very itchy.
This is a commensalistic relationship between sharks and remora. It is considered commensalism because one organism is benefited and the other is neither benefited nor harmed. The remora rides on the shark to save energy while nothing good or bad happens to the shark.