Which of these functions is suitable to check whether a wrapped value is populated or blank?

The function that is suitable for checking whether a wrapped value is populated or blank is "IsPresent()". This function is specifically designed to evaluate whether a value is both defined and not empty.

Using "IsPresent()" effectively communicates the intention to check for the presence of a value in a way that considers both conditions, making it the most appropriate choice. "IsEmpty()" is useful for checking if a collection is empty but does not cover wrapped values in the same way. "IsNull()" will only indicate if a value is null, which may not provide a complete picture for wrapped values. "IsDefined()" checks if a variable has been declared, but again does not convey whether it is populated or blank.

Therefore, "IsPresent()" is the correct option for determining if the wrapped value is valid and contains meaningful data.