An ameba is a single-celled organism. it uses its cell membrane to obtain food from its environment, digests the food with the of organelles called lysosomes, and uses other organelles to process the digested food. from this, we can best infer that

(1) all single-celled organisms have lysosomes to digest food
(2) amebas are capable of digesting any type of food molecule
(3) single-celled organisms are as complex as multicellular organisms
(4) structures in amebas have functions similar to organs in multicellular organisms

According to me answer no 4  is correct.

Explanation:

single cell amoebas can perform all life functions capture the food, digestion, respiration, excretion, and reproduction also. These all are similar to multicellular animals.

parasites can detrimentally affect their host, but also must not allow their host to die before they can complete their life cycle. some parasites have complex life cycles with many different hosts, and have had to find ways of persisting in many different environments during the change from one host to another. ectoparasites live outside the body of the host, and can more easily  disperse, but are  more exposed to predators, parasites, parasitoids. endoparasites live inside the body of the host, and are therefore protected from the outside environment. but they can be  attacked by the host's immune system. they have therefore developed  mechanisms for dispersal such as  complex life cycles.