$\backslash$table$[[\backslash$table$[[$To$],[$From$],[$Morgantown$]],\{$

$\backslash$table$[[$Coal$],[$Valley$]]\},$Coaltown,$\{$

$\backslash$table$[[$Coal$],[$Junction$]]\},$Coalsburg,Time left $0$:$18$:$1],[$Sunoly$],[,50,,30,,60,,70,$upply$],[$Youngstown$,30,,5,,,,,,35],[,20,,80,,10,,90,60],[$Pittsburgh$,,100,40,,20,,,],[,,,40,,80,,30,],[$Demand$,30,45,\frac{5}{26},,20,,25]]$

What is the improvement index for Morgantown to Coalsburg?

a$.130$

b$.100$

c$.-70$

d$.160$

e$.-80$