Amoving, multicellular organism that cannot make its own food most likely belongs to which kingdom?

It would belong to Animalia.
Organisms in Animalia are heterotrophs which means they can’t make their own food. It could technically also belong to Protista or Monera because some of the microorganisms in them are multicellular, but all of the organisms in Animalia are multicellular so it would be the most likely.

Three reasons of the deaths of native americans: new illnesses that their immune systems couldn't cope with. genocides so the settlers could have the good land.starvation from lack of rations and poor infertile land on resevations

Your answer is going to be b.