What is the purpose of a type check in data validation?

• A. It ensures the input is present.
• B. It ensures the input is the correct data type (for example, number or text).
• C. It verifies the input matches a specific pattern.
• D. It confirms the data length is within allowed bounds.

Answer: (B)

Verifying the data type of input is about making sure the value you receive has the kind of data your program expects, such as a number or a text string. This protects operations that rely on that type—like doing arithmetic with numbers or performing string manipulations—from failing or giving wrong results. For example, if a field is supposed to be a number, a type check will catch inputs like "twenty" or "12 apples" before you try to treat them as numbers.

This is different from checking that something is present, or that it matches a specific pattern, or that its length is within bounds. Presence checks only verify something was entered. Pattern checks confirm the format (such as an email pattern). Length checks verify how many characters or digits are there. Type checking specifically targets the kind of data, which is essential for ensuring downstream processing can proceed safely.