Reduced cost: Select the correct statement:

The coefficient for $D$ has to be $105$ or more in order for $D$ to be attractive The coefficient for $D$ has to be $15$ or more in order for $D$ to be attractive The coefficient for $D$ has to be $15$ or less in order for $D$ to be attractive The coefficient for $D$ has to be $105$ or less in order for $D$ to be attractive