In Revising the Opportunity Cost Table of the Assignment Problem

In revising the opportunity cost table of the assignment problem, after drawing lines through all of the zeros

A) the smallest uncovered number is added to all zeros.
B) the smallest uncovered number is added to all uncovered numbers.
C) the largest uncovered number is added to all uncovered numbers.
D) the smallest uncovered number is added to all numbers at the intersection of lines.