Which of the following is/are not characteristic of prokaryotic cells?
a. complex
b. nucleus
c. organelles
d. all of the above
(i think it’s complex, but i’m having my doubts.)

Complex is the right answer

the correct answer is c   with the systems

when atoms of different types of elements join together, they make molecules called compounds. water consists of compound molecules made up of 2 hydrogen atoms and 1 oxygen atom. this is why it's called h2o. water will always have 2 times the number of hydrogen atoms as oxygen atoms.