Confectioners sugar, also known as powdered sugar, is the type of sugar that increases the spread when making cookies with the spread method. This is because it has a fine texture and dissolves quickly, allowing for greater spread of the dough.
- Fine sugar is slightly coarser and does not allow as much spread.
- Cube sugar is compressed into cubes and is not suitable for spreading in cookies.
- Granulated sugar is the standard sugar, but it does not increase spread as much as confectioners sugar.
Thus, the correct answer is Confectioners sugar.