B. One
because an independent variable is something you change. So in a scientific experiment you only change one thing. If you happen to change more than one thing then the test becomes unfair therefore you should repeat and make sure that only one thing is changed this time.
Answer:
D. Eukaryote
Explanation:
An organism that has membrane-bound organelles will have more complex organelles like mitochondria, Golgi apparatus, and ER. These are known as Eukaryotes. Additionally, they will have a nucleus that has the DNA coiled inside. Prokaryotes do not have membrane-bound organelle and the DNA floats in the cytoplasm. Most plants and animals are eukaryotes and all multicellular organisms are too.