In which interaction is the host harmed? commensalism competition mutualism parasitism

It is 100% Parasitism.

Parasitism is a relationship between two organisms were one organism, or the parasite feeds at the cost of the other organism or host. Ticks and dogs, these are two things a pet owner dreds to see. The tick is considered the parasite because it can get on to a dog and carries diseases with it. One disease is called the Rocky Mountain spotted fever, this can be harmful to the dog and can have it become very ill.

d i think its   answer d