Final answer:
The search 'students AND alcohol OR liquor' will yield the most articles, as the OR operator expands the search to include articles containing either 'alcohol' or 'liquor' along with 'students'.
Step-by-step explanation:
The keyword search that will retrieve the most articles is b. students AND alcohol OR liquor. This is because using the OR operator in a search includes results that contain either of the terms combined with it — in this case, articles containing 'alcohol' or 'liquor'. This broadens the search and yields a larger number of articles. The AND operator narrows the search by retrieving only articles that contain both keywords 'students' and 'alcohol'. In contrast, the NOT operator excludes articles with a certain term, so 'students AND alcohol NOT beer' would eliminate any articles that also mention 'beer', further narrowing the results.