Five Jobs Are Waiting for Processing Through Two Work Centers

Multiple Choice

Five jobs are waiting for processing through two work centers. Their processing time (in minutes) at each work center is contained in the table below. Each job requires work center Alpha before work center Beta. According to Johnson's rule, what is the optimum sequence of jobs and the minimum time for completion of all jobs?
$$\begin{array} { | c | c | c | } \hline \text { Job } & \text { Alpha } & \text { Beta } \\\hline R & 20 & 10 \\\hline \mathrm { S } & 25 & 35 \\\hline \mathrm { T } & 50 & 20 \\\hline \mathrm { U } & 15 & 35 \\\hline \mathrm { V } & 55 & 75 \\\hline\end{array}$$

A) V-T-S-U-R; 225
B) U-R-T-S-V; 175
C) R-S-T-U-V; 240
D) U-S-V-T-R; 200
E) none of the above