The unit cost is cost of 1 unit of a product, here its cost of 1 pound of sugar.
In first case unit cost is $1.07.
In second case, cost of the 2 pound = $2.02, or cost of 1 pound = [2.02/2] = $1.01.
In third case, cost of the 3 pound = $2.79, or cost of 1 pound = [2.79/3] = $0.93.
We can see that as the quantity is increasing unit cost is decreasing.