ALL OF THE ABOVE! All include human activity
E (I am sorry if I got this answer wrong).
Answer:
a 10th of a second delay between hearing the bell and noting the position of the pendulum (and vice versa)
Explanation:
Using a pendulum that hit a bell upon reaching its outer limits, Wundt demonstrated a 10th of a second delay between hearing the bell and noting the position of the pendulum (and vice versa), and it was during that very brief period that a mental process occurred.