On the basis of the trend shown in the chart below, which of the following actions, if any, would be appropriate for a quality manager to take?

On the basis of the trend shown in the chart below, which of the following actions, if any, would be appropriate for a quality manager to take?
The correct answer is A: the chart shows a normal reading with out special trend, out of the limit reading, etc.
Sorry I ment the correct answer is D.