Answer:
a. Not enough subjects
Explanation:
In the context, it is given that in a factory, a molding machine is not working properly. The molding machine produces a gun made of plastic. But the machine was produces a defective piece about a third of he time it produces the gun.
The mechanic adjusted and repaired the stamping pressure and ran only one gun through which came out to be fine. But there was an error in the conclusion of the repair mechanic as she did run the machine only one time. She did not have enough subjects and should have run many times to see if the error still exists, as the machine showed error only about a third of the time during the process.
Thus the error in the experiment includes the lack of the enough of the subjects. We cannot come to the conclusion only with one time success.
