$\underline{\textbf{Answer:}\Rightarrow}\;\mathbf{d.}$
The Remote procedure calls are used in distributed computing, wherein a computer program causes a subroutine to execute in a $\color{magenta}{\text{different address space}}$ (on another computer), which is coded as if it were a local procedure call.
RPCs are a form of inter-process communication (IPC), in that different processes have different address spaces: if on the same host machine, they have distinct virtual address spaces, even though the physical address space is the same; while if they are on different hosts, the physical address space is different. Many different (often incompatible) technologies have been used to implement the concept.
Quoting as it is from Wikipedia.
So, it means that the virtual address space just needs to be different. So, it can be on the same system or another system as well.
https://users.cs.cf.ac.uk/Dave.Marshall/C/node33.html
https://web.cs.wpi.edu/~cs4514/b98/week8-rpc/week8-rpc.html
https://en.wikipedia.org/wiki/Remote_procedure_call