Answer:
subliminal perception.
Explanation:
Subliminal perceptions, also known as subliminal messages, are messages, either visual or auditory, that are presented just beyond the threshold of human perception. A subliminal perception may not be audible enough that the conscious mind might register it but be audible enough for the subconscious mind.
For example it might be an image transmitted briefly and unperceived consciously and yet perceived unconsciously.
Various reasons why five trained individuals might come up with different readings are - while carrying out an experiment, the accuracy with which each individual perform an experiment varies. The readings in different instruments used while performing an experiment also differs.
There is certain percentage of error that occurs while carrying out an experiment by each of the individual. Physical conditions such as temperature, pressure changes from one place to another where the experiments are being carried out.
Answer: A. before history was written.
Explanation:
I'm not sure if you need an explanation, but prehistoric means "very old or out of date." Hope this helps, Good luck! :)