A Campaign Manager for a Political Candidate Must Arrange the Shipment

Multiple Choice

A campaign manager for a political candidate must arrange the shipment of 150 cartons of campaign buttons from three button producers to three campaign headquarters. The supplies and demands, and the per-carton transportation costs, are shown below: Which of the following is a constraint for the suppliers (button producers) ?

A)
$2 X _ { 11 } + 5 X _ { 12 } + 6 X _ { 13 } = 50$
B)
$9 \mathrm { X } _ { 11 } + 3 \mathrm { X } _ { 12 } + 7 \mathrm { X } _ { 13 } = 50$
C)
$X _ { 11 } + X _ { 12 } + X _ { 13 } = 50$
D)
$X _ { 12 } + X _ { 22 } + X _ { 32 } = 70$
E) all of the choices