Detailed Explanation:

For a large population, a simple random sample of 400 charts would be sufficient to obtain representative data for statistical analysis:

Option B:Selection of 400 charts using a simple random sampling method

Simple random sampling ensures each patient has an equal chance of selection, providing unbiased and representative results while being more manageable than reviewing all 8,000 records.

Option A: Selection of patients who had a visit during the last month of the year

This could lead to biased results, as it would not be representative of visits throughout the year.

Option C: Selection of 800 patients using a snowball sampling method

Snowball sampling is typically used for hard-to-reach populations and is not appropriate for this scenario.

Option D: Selection of the entire population

Auditing all records would be time-consuming and unnecessary when a statistically valid sample can provide reliable results.