Which of the following is the most efficient means of product quality inspection?1. Acceptance sampling2. 100% inspection3. Variable sampling4. a and c

The most efficient means of product quality inspection can vary depending on the specific circumstances, such as the nature of the product, the production volume, and the acceptable level of risk. Here's a brief overview of each method:

1. Acceptance Sampling: This is a statistical quality control method that involves inspecting a random sample of the goods instead of the whole batch. It is less time-consuming and less costly than 100% inspection. However, there's a risk that some defective items may not be detected.

2. 100% Inspection: This involves inspecting every single item. While this method can ensure that all defective items are detected, it is very time-consuming and costly, and may not be feasible for large production volumes.

3. Variable Sampling: This involves inspecting a variable number of items, depending on certain criteria. This method can be more efficient than 100% inspection, but there's still a risk that some defective items may not be detected.

4. a and c: This would involve using a combination of acceptance sampling and variable sampling. This could potentially provide a good balance between efficiency and thoroughness.

Without more specific information, it's difficult to definitively say which method is the most efficient. However, in general, a combination of methods (option 4: a and c) can often provide the most effective balance between detecting defects and maintaining efficiency.