Final answer:
The ticket task button to edit the quantity of a line item could be any of the provided options, but typically 'Edit Quantity' or 'Quantity Modifier' are used. Without specific context of the system being used, it's best to refer to the documentation for clarity.
Step-by-step explanation:
The ticket task button used to edit the quantity of a line item is typically labeled as Edit Quantity, Adjust Line Item, or Quantity Modifier, and less commonly as Update Item. However, without specific context, such as the software or system being referenced, it is not possible to provide a definitive answer. Typically, Edit Quantity or Quantity Modifier would be the most intuitive labels for such a function, but the exact label can vary depending on the program or point of sale system in use. When working with an unknown system, it's best to consult the user manual or help documentation for the correct procedure to edit line item quantities.