Answer:
C - By describing how the houses act as barricades
Step-by-step explanation:
"(...)Solid and square to the world the houses stand, their windows blocked with venetian blinds. Nothing will move them (...)".
"Nothing will move them" means that nothing could ever penetrate those houses. Not the sound of cars nor the voices.
The houses stand alone, solid and square, with windows blocked. You can't get in or out, you are trapped, you are alone.