Consider the linear programming problem:

Minimize $z=0\mathrm{.}4x_1+0\mathrm{.}5x_2$

Subject to the constraints:

$0\mathrm{.}3x_1+0\mathrm{.}1x_{2}2\mathrm{.}7$

$0\mathrm{.}6x_1+0\mathrm{.}4x_{2}6$

$0\mathrm{.}5x_1+0\mathrm{.}5x_2=6$

$x_1,x_{2}0$

Let $y_1,y_2,y_3$ be dual variables corresponding to the constraints $1,2,$ and $3$ respectively. Then

both $y_2$ and $y_3$ are unrestricted in sign

only $y_3$ ts unrestricted in sign

None of these

both $y_1$ and $y_3$ are unrestricted in sign