Final answer:
Eukaryotic organisms were able to evolve after the mass extinction through sexual reproduction creating more variety among offspring, cell specialization in colonies, and the emergence of multicellular organisms. The mass extinction at the end of the Precambrian era paved the way for new organisms to emerge in the Cambrian explosion.
Step-by-step explanation:
Eukaryotic organisms were able to evolve after the mass extinction that ended the Precambrian era because of several factors. One reason is that sexual reproduction created more variety among offspring, increasing their chances of survival when the environment changed. Additionally, some cells started to live together in colonies and specialize in different jobs, making them more efficient as a colony. By forming multicellular organisms, they became bigger, more efficient, and capable of doing more than single-celled organisms. The mass extinction at the end of the Precambrian era opened up opportunities for new life to emerge, leading to the Cambrian explosion of new organisms.