Final answer:
The question correctly answered by 'the Cambrian Explosion' is 'When did complex multicellular life appear?' This period marked a significant evolutionary milestone with theories suggesting environmental changes and genetic advances as possible causes. Despite mass extinctions, the diverse life forms that evolved then laid the groundwork for species today.
Step-by-step explanation:
The correct question that corresponds to the answer 'the Cambrian Explosion' is: c) When did complex multicellular life appear? The Cambrian Explosion refers to a remarkable period in Earth's history, approximately 541 million years ago, when there was a rapid increase in the diversity of multicellular organisms. Understanding the Cambrian Explosion involves recognizing its significance in evolutionary biology and the theories proposed to explain its occurrence.
Two theories attempting to explain the cause of the Cambrian explosion are:
- Environmental changes like rising atmospheric oxygen levels and increases in oceanic calcium concentrations that may have created more suitable conditions for animal life.
- Genetic and developmental advances such as the evolution of Hox control genes that could have increased the morphological complexity allowing for a diversity of animal body plans.
The reason that most of the extant animal phyla today evolved during the Cambrian period, despite subsequent mass extinctions, is in part due to the vast diversification and evolution that set the stage for future resilience and adaptation across multiple species.