$\backslash$table$[[$Basic$,Z,x1,x2,x3,x4,$S$1,$S$2,$S$3,$RHS$],[Z,1,0,0,6,17,4,0,1,170],[x2,0,0,1,0\mathrm{.}7,1\mathrm{.}7,0\mathrm{.}4,0,-0\mathrm{.}1,15],[$S$2,0,0,0,0\mathrm{.}5,2\mathrm{.}5,0,1,-0\mathrm{.}5,3],[x1,0,1,0,0\mathrm{.}6,0\mathrm{.}6,0\mathrm{.}2,0,0\mathrm{.}2,10]]$

For this minimization problem, which variable should be entering as basic variable in the next iteration?

a$.x2$

b$.x3$

c$.x4$

d$.x1$

e$.$ None of the above