Final answer:
Multicellularity was the second development that enhanced the Cambrian Explosion. It allowed cells to live together in colonies and specialize in different jobs, leading to larger and more complex organisms.
Step-by-step explanation:
The second development that enhanced the Cambrian Explosion was the emergence of multicellularity. This allowed cells to live together in colonies and specialize in different jobs, making them more efficient as a colony. Multicellularity led to larger and more complex organisms, which contributed to the rapid evolution and diversification of animal species during the Cambrian period.