Recent archaeological excavations have revealed that ancient civilizations in the fertile crescent developed complex irrigation systems far earlier than previously believed. These systems allowed for extensive agricultural surpluses, supporting larger populations and specialized labor within these societies.

✓ Correct Answer: Option B

The passage directly states that early complex irrigation systems allowed for surpluses, larger populations, and specialized labor. This strongly implies that these systems were critical for the development and complexity of those societies. Option B is a direct inference from this causal chain described.