Final answer:
The main downside of using a circular array implementation of a queue is the limited queue size, which is predefined and cannot grow dynamically, leading to potential overflow scenarios.
Step-by-step explanation:
The main downside to using a circular array implementation of a queue is c) Limited queue size. In a circular array, the size of the queue is fixed at the time of its creation, meaning that the number of elements it can hold is limited. This is because the array's maximum size must be specified and allocated in memory beforehand, and it cannot dynamically grow to accommodate more elements than this maximum.
Contrary to dynamic data structures like linked lists, where nodes can be added indefinitely, a circular array exhausts its capacity once it's filled, even if old elements have been dequeued. If the queue fills up, new data cannot be enqueued until space is made available by dequeuing existing elements. This limitation requires careful management to avoid overflow scenarios, which can lead to data loss or the need to handle 'queue full' situations in code.