Several Studies Indicate That Brain Activity Preparing for a Movement

Multiple Choice

Several studies indicate that brain activity preparing for a movement starts before the conscious decision to make the movement.Why is the interpretation of results uncertain?​

A) The results vary drastically from one culture to another.
B) ​Researchers cannot accurately measure the time of a brain activity.
C) ​People cannot accurately report the time when they made the movement.
D) ​Voluntary decisions are gradual and difficult to pinpoint in time.