Answer:
The correct option is D) Ruling out rival hypothesis
Step-by-step explanation:
In scientific approaches, ruling out rival hypothesis can be described as before explaining our hypothesis, we annul or give justifications for the annulment of the other hypothesis which exist for that claim. Before offering our explanations, we should first try to disprove the former explanations or depictions.
In the scenario discussed in the question, scientists tend to first annul the former hypothesis about death by providing justifications that the visions which we see at the time of death are due to the release of massive endorphins.