For questions like these, can we use the immune response as a defence adaption? I thought we would have to use the ones listed in the dot-point about defence adaptations such as cell death to pathogen, inflammation response, phagocytosis and lymph system.
Oooo that's a good point. Yes I believe you're right, since they used that exact terminology in the question. (and those things are technically still host responses as they are still defence mechanisms of the host against pathogens)
Since this is a three marker though, I would only use inflammation response and phagocytosis - as this is what you'd typically imagine occurring for a patient with malaria. [The Anopheles mosquito would bite the skin, breaching the skin barrier and inducing a inflammation response. Macrophages would engulf any entering foreign material and destroy it using lysosomes etc.]