What is the purpose of the SASFILE statement?

What is the purpose of the SASFILE statement?
A . It requests that SAS data set be opened and loaded into SAS memory one page at a time
B . It requests that a SAS data set the opened and loaded into SAS memory one variable at a time
C . It requests that a SAS data set be opened and loaded into SAS memory one observation at a time
D . It requests that a SAS data set be opened and loaded into SAS memory in its entirety

Answer: D