Which of these statements is best?

In the assignment problem, the costs for a dummy row will be equal to the lowest cost of the column for each respective cell in that row.

Assignment problems involve determining the most efficient assignment of people to projects, salesmen to territories, contracts to bidders, and so on.

The objective of an assignment problem solution most often is to maximize the total costs or time of performing the assigned tasks.

The objective of an assignment problem solution most often is to minimize the number of assigned tasks.