Final answer:
Upon administration of IV euthanasia solution, the usual sequence is loss of consciousness followed by cessation of breathing and finally cardiac arrest due to the disruption of electrochemical gradients in the heart by excess potassium.
Step-by-step explanation:
When IV euthanasia solution, commonly containing a high concentration of potassium, is administered, the sequence of events typically begins with a loss of consciousness due to the rapid onset of the anesthetic component in the solution. This is swiftly followed by cessation of breathing as the respiratory center in the brain is affected. Finally, cardiac arrest occurs because the elevated levels of potassium in the bloodstream disrupt the normal electrochemical gradients that are essential for the contractions of the heart muscle. This disruption leads to the heart's inability to pump blood, quickly leading to death.
As euthanasia involves ethical and medical considerations, any discussion about the process is sensitive and complex. Active euthanasia, which is referred to in the question, is a more direct form of euthanasia where life-terminating drugs are used. In the context described, the correct order of events upon administering IV euthanasia solution is a) Loss of consciousness, cessation of breathing, cardiac arrest.