Lice on humans and ticks on the dogs are example of :
Mutualism
Commensalism
Ectoparasite
Endoparasite
Ectoparasites -
Parasites that feed on the external surface of the host organism is called ectroparasite.
- wherein
The most familiar examples of this group are the lice on humans and the ticks on the dogs. Cuscuta, a parasitic plant that is commonly found growing on hedge plants, has lost its chlorophyll and leaves in the course of evolution. It derives its nutrition from the host plant which it parasitises.
So, Correct option is 3