What class would ensure that a column takes up the full width of the row in Bootstrap 3?

In Bootstrap 3, the grid system is based on a series of classes that allow you to create responsive layouts using a twelve-column system. The class "col-12" is specifically designed to instruct an element to span all twelve columns of the grid. Therefore, when you apply this class to a column, it will effectively take up the entire width of the row in which it is contained.

Using "col-12" ensures that the column stretches from the left edge to the right edge of its parent container, allowing for a full-width display in the layout. This is particularly useful when you want to create large or full-width elements such as hero sections, banners, or any layout that requires maximum width utilization.

Other options like "col-full," "col-wide," and "col-100" do not exist in the Bootstrap 3 framework, and hence, wouldn't function to achieve full-width columns. The naming conventions of Bootstrap's grid system are specifically defined, and only the established classes like "col-12" are recognized for column formatting and responsiveness in that version.