directory
A telephone
B listing
C computer
D names
Correct Option - B
ExplainationA directory is a listing of names or things, so (choice b) is the essential element. A telephone (choice a) often has a directory associated with it, but it is not essential. A computer (choice c) uses a directory format to list files, but it is not required.Names (choice d) are often listed in a directory, but many other things are listed in directories, so this is not the essential element.