Final Answer:
After Fisher and Venus begin searching for clean water, they encounter challenges or obstacles that compel them to return to their flat. So, the correct answer is c) they are forced to go back to their flat.
Step-by-step explanation:
After Fisher and Venus embark on their quest for clean water, they face challenges that force them to return to their flat. The narrative suggests that their pursuit encounters obstacles, possibly indicating a scarcity of clean water sources or external threats hindering their search. The need to go back to their residence implies a sense of urgency or a lack of viable alternatives, adding suspense to the storyline. This turn of events may introduce new plot elements or conflicts that shape the characters' journey. The story could unfold further as Fisher and Venus navigate the complexities of finding clean water, providing a foundation for subsequent developments in the narrative.
Therefore, the correct answer is c) they are forced to go back to their flat.