Life on Land Life Test

What best describes the era called the “Cambrian explosion”?
(a)A vast array of multicellular organisms came into being and began to occupy many niches.
(b)It’s a time in Earth’s history where life was limited to oceans, lakes, and rivers.
(c)The fossil record suggests the first mammals arose during this time.

Answer
(a)A vast array of multicellular organisms came into being and began to occupy many niches.