Which data validation step is crucial to ensure that all entries in a customer email column are correctly formatted?

A regular expression (regex) pattern is commonly used to validate email formats by checking for typical email components (e.g., "[email protected]"). Validating data entries with regex ensures that each email address follows a standard pattern, preventing incorrectly formatted entries from passing through. This step is essential for data quality and accuracy, particularly in fields requiring specific structures, like email addresses in customer data. Option A is incorrect as it checks for completeness, not format accuracy. Option C is incorrect as removing duplicates is a data cleaning step, not a validation step for format. Option D is incorrect as converting to lowercase standardizes data but doesn’t ensure correct email format. Option E is incorrect as checking for numerical entries doesn’t confirm valid email structures.