When you create a text box field, you should use the maxlength attribute to:

Using the maxlength attribute in a text box field is essential for defining the maximum number of characters that a user can input into that field. This attribute directly sets a cap on the amount of text accepted, which can help in several ways, such as ensuring data integrity, preventing overly long input that could disrupt the design of the interface, and improving user experience by providing immediate feedback on allowable input length.

By applying this attribute, developers can guide users toward valid input lengths that conform to database requirements or business rules. It's a straightforward way to enhance data validation without requiring additional Javascript or back-end validation, providing a more seamless user experience.

While options that suggest specifying a minimum number of characters, limiting the number of lines, or controlling the size of the field may certainly be considerations in form design, they do not accurately capture the specific function of the maxlength attribute. Hence, the correct choice accurately reflects the purpose of this attribute within HTML forms.