At the Millbrook High School cafeteria, students proceed along a series of stations in a single line: (1) get tray and utensils, (2) choose food, (3) select beverage, (4) pay. 

The school is concerned that students are taking too long to get their meal. The school has analyzed the capacities of each of the four steps in isolation and found there exists sufficient capacity at each resource in isolation. Which of the following is most likely to be causing the congestion? 

a. The bottleneck is probably at the last station because capacity is reduced the most when the bottleneck is at the end of the process. 

b. The implied utilization of the bottleneck is too low. 

c. Due to variability in processing times, both blocking and starving could be occurring. 

d. The process must be demand-constrained. 

e. The stations have similar utilizations.