Answer:
d. parasitism; mutualism
Explanation:
When an organism derives nutrition from the living tissues of other organisms, the association is called parasitism. Here, the parasite gets nutrition and/or other benefits while the host organism is harmed. When the blood, milk, and fur of livestock are used by tribesmen, the livestock is harmed and the interaction is called parasitism. The parasite (tribesmen) keep the host (livestock) alive to obtain the benefits.
Mutualism is a beneficial association between the organisms of two species wherein both the associated organisms are benefited. Since the tribesmen protect the livestock and feed them to derive benefits from them, the association is mutualism. Livestock is fed and protected while the tribesmen obtain blood, milk, and fur from them. In this way, both are benefited.