Please help me, I been stuck on this.

All living organisms are composed of a. only one cell. b. at least 100 cells. c. at least three cells. d. one or more cells.

The earth consists of a variety of different organisms. despite their diversity, however, some similarities on the structural and metabolic levels may be seen. these similarities can be attributed to a. similarities among organisms in their proteins and nucleic acids. b. the ability of organisms to readily adapt to sudden environmental changes. c. similarities in organisms' habitats and niches. d. the ability of all organisms to interbreed and produce new species.

Cells destroy body cells infected by a virus or bacteria. killer t t memory t none of the above