Question: They cooked extra food for tonight _____ they expected more people to show up.
Correct Answer: since
This question tests conjunctions (logical connectors). "Since" is correct because it explains the reason for cooking extra food (they expected more people). It functions similarly to "because" in this context.

Incorrect Answers:
- however - This indicates contrast, but the sentence requires a reason, not opposition.
- nonetheless - This means "despite that," which doesn't fit the context of giving a reason.
- although - This introduces a contrast, not a causal relationship like the sentence.