b. The meaning of the entries in rows 1 and 2.

Row 1 indicates that constraint E1 is loose and changing its right side will not affect the objective function.

Row 2 indicates that increasing the right side of E2 by 1 will increase the objective function by 0.75.

c. The figure shows the original objective function lines and the lines at the limits of the range. The solution remains optimal in the range.

d. When the right side of E3 increase to 16, only one point is feasible and must be optimal. For any further increase there can be no feasible solution.