Use the Information in the Table (All Times Are in Days)to

Use the information in the table (all times are in days) to determine the lowest extra cost for an 18-day project if the base cost for each activity finished in normal time is $1,000. $\begin{array}{|l|l|l|l|l|} \hline&\text { Normal }&\text {Minimum}&\text { Crash Cost }\\ \text {Activity}&\text {Time}&\text {Time}&\text { (\$/day) }& \text { Predecessor }\\\hline \mathrm{A}& 10 & 6 & \$ 70 & -- \\ \hline \mathrm{B} & 6 & 3 & \$ 40 & -- \\\hline\mathrm{C} & 2 & 2 & - &\mathrm{B } \\\hline\mathrm{D} & 4 & 2 & \$ 60 &\mathrm{ C } \\\hline \mathrm{E} & 6 & 4 & \$ 80 &\mathrm{ A } \\\hline\mathrm{F} & 8 & 5 & \$ 90 & \mathrm{D},\mathrm{ E }\\\hline \end{array}$

A) $400
B) $420
C) $440
D) $460