Final answer:
Continuous review inventory systems do not plan for a longer period; this is not their advantage over periodic systems. They do, however, require less safety stock due to more frequent monitoring, which reduces uncertainty.
Step-by-step explanation:
One disadvantage of continuous review inventory systems as compared to periodic review systems is that continuous review does not inherently plan for a longer period. The main difference lies in how inventory levels are monitored; a continuous system checks inventory levels after each transaction while a periodic system reviews at fixed intervals. Counter to the claim in option (a), continuous review systems typically require more frequent monitoring, which does not correlate to planning for longer periods.
Instead, it allows for a continuous update on inventory status, which may lead to more frequent reordering but with smaller quantities. Regarding option (b), one advantage of continuous review systems is indeed that they require less safety stock because the inventory levels are monitored more frequently, reducing the uncertainty and variability that comes with longer intervals between reviews in periodic systems.