I think it is repeatable, testable, observable
Answer: Blood plays a very important role before cellular respiration. The blood provides oxygenated blood for the aerobic processes that takes place during cellular respiration. Glycolysis, link reaction, Kreb's Cycle and Electron Transport Chain are all the aerobic process of Cellular respiration that requires oxygen. Without blood aerobic cellular respiration cannot occur as the source of oxygen is blood. The blood provides oxygen before cellular respiration. After cellular respiration the waste materials are carried away by blood only.
Hence, blood plays an important role before cellular respiration.
DNA replication begins when something called Helicase (an enzyme) unwinds the helix structure of the DNA. It does this so that Primase can then come along and set down an RNA primer.
The answer u r looking for is- B, The electron transport chain stops, stopping the citric acid cycle. Hope I’ve helped ;)