Which accomplishment most likely helped the Incan emperor maintain rule over widespread lands?

A The Inca built a vast network of roads
B The Inca developed a uniform system of writing
C The Incan emperor claimed ownership of all land
D The Incan emperor requires all subjects to serve in the army.

My answer is D

3 answers

I disagree. Which of those answers show how the emperor could keep control over large areas?
The Inca emperor claimed ownership of all land
its A) The Inca built a vast network of roads.
I really hope you ace this test :)