Explanation:

The Edit Lines Field Set Name field on the Quote object specifies the Field Set from the Quote Line object to use for controlling which fields appear as columns in the Quote Line Editor grid.

In other words:
1. The fields included in the referenced Field Set will become visible columns on the Quote Line Editor page (the main table you see when you click “Edit Lines” on a quote).
2. The user sees these fields while editing quote lines, adjusting quantities, discounts, etc.

So it directly affects which quote line fields are displayed on the Edit Lines screen. That makes C correct.

❌ Why Others Are Incorrect

A. The fields that trigger a calculation event to occur
→ Incorrect. Calculation triggers depend on field-level configuration (e.g. being marked as a pricing or costing field), not on the field set.

B. The fields that appear in the Quote Line Drawer
→ Incorrect. The Quote Line Drawer is controlled via the Line Editor Field Set Name field on the Quote object (for the drawer) or the “Line Editor Drawer” field set on Quote Line—not the Edit Lines field set.

D. The Quote fields that may be edited
→ Incorrect. This is about Quote Line fields, not fields on the Quote object itself.