The system/370 assembler language

A)  allows the programmer to write base registers and displacements explicitly in the source program.
B)  is a term that refers to the control programs of an operating system.
C)  allows multiple programs to reside in separate areas of core at the same time.
D)  is used to remember which of the general-purpose registers are currently available as base registers, and what base addresses they contain.

Correct Answer :   allows the programmer to write base registers and displacements explicitly in the source program.