a quality control manager wants to determine the percentage of a defective light bulbs in the production line which of the following sampling methods would most likely lead to a valid inference?
A. Testing the last 4,000 bulbs in the production line
B. Retesting 100 light bulbs that have already been tested
C. testing every 15th light bulb in the production line.
D. Testing the first 2000 light bulbs in the production line