Final answer:
John's difficulty in following the biology lecture is best exemplified by psychological noise.
Step-by-step explanation:
The best option that exemplifies the situation described in the question is psychological noise. Psychological noise refers to internal distractions that prevent effective communication, such as fatigue, stress, or lack of concentration. In this case, John's difficulty in following the lecture is directly caused by his sleep deprivation, which is an internal factor affecting his cognitive abilities.
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