Solve the Standard Minimization Problem Using Duality $c = 0.4 s + 0.6 t$

Multiple Choice

Solve the standard minimization problem using duality.
Minimize $c = 0.4 s + 0.6 t$
Subject to $$\begin{array} { l } 0.2 s + 0.1 t \geq 1 \\0.15 s + 0.3 t \geq 1.5 \\10 s + 10 t \geq 80 \\s \geq 0 , t \geq 0\end{array}$$

A) $c = 3.6$ , $s = 6$ , $t = 2$
B) $c = 2.8$ , $s = 6$ , $t = 2$
C) $c = 1.2$ , $s = 6$ , $t = 2$
D) $c = 4.4$ , $s = 2$ , $t = 6$
E) $c = 2.8$ , $s = 2$ , $t = 6$