Final answer:
An indexed file exploits disk capabilities to directly access any block of a known address using an index. So option D is correct..
Step-by-step explanation:
The indexed file exploits the capability found on disks to access directly any block of a known address. Unlike sequential files that require reading through the previous blocks to reach a specific block, an indexed file uses an index to locate the desired block directly. This index contains the addresses of the blocks and their corresponding keys, allowing quick access to specific blocks.
Direct files, also known as random access files, allow the system to directly access a block of data on disk using a known address without having to read through other data sequentially. This method is highly efficient when you need to access data in a non-sequential order. While sequential files must be read in order, and indexed sequential and indexed files use indices to improve access times to sequential files, direct files provide the quickest method to retrieve or update data because of the direct approach to any block of data.