Final answer:
a.) ram The component that can cause a bottleneck if it's not available in sufficient quantity is RAM; it is shared by all processes and essential for fast data transfer.
Step-by-step explanation:
The correct answer is option a.) RAM. RAM, or Random Access Memory, is a critical component of a computer system that temporarily stores data for quick access by the processor. When there isn't enough RAM, the system has to use the much slower hard disk to store and retrieve data, which can cause a significant bottleneck.
This issue is known as thrashing, where the operating system moves data between the RAM and the hard disk (swap space) to juggle multiple running processes.
Due to its role in providing fast access to data for all the running processes and the necessity of data exchange among system components to use RAM, insufficient RAM leads to competition over this resource, slowing down the overall system performance.