The problem describes a scenario where a restaurant leaves comment cards on all its tables for customers to fill out voluntarily. The question asks what type of sampling method this represents.

1. Problem Description

The problem describes a scenario where a restaurant leaves comment cards on all its tables for customers to fill out voluntarily. The question asks what type of sampling method this represents.

2. Solution Steps

A simple random sample requires that every member of the population has an equal chance of being selected. This is not the case here, as only customers who choose to fill out the card are included in the sample.

A stratified random sample involves dividing the population into subgroups (strata) and then taking a random sample from each stratum. This is not happening here.

A cluster random sample involves dividing the population into clusters and then randomly selecting some of the clusters to sample. This is also not the case here.

A systematic random sample involves selecting samples at regular intervals. This is also not the case here.

Since the customers are self-selecting, this does not fit any of the standard sampling methods. Therefore, the best answer is "None of the above."

3. Final Answer

None of the above