Pls help me with these qs, its an really important test for me!!! TY

Which best describes the digestive system of arthropods? a incomplete, two openings b complete, one opening c two-way, one opening d one-way, two openings

According to the cell theory, which describes cells? a. all organisms are composed of multiple cells. b. all cells have the same structure and function. c. cells are found in everything on earth. d. living organisms are not created spontaneously

Which of the following is a period in the paleozoic era? devonian cambrian permian all of the above