During the late Precambrian era, enough a
escaped from volcanoes to begin
period of
global warming.

Eventually, enough CO2 escaped from volcanoes to begin a period of global warming; melting opened a great variety of new niches. When CO2 levels were high, they created a greenhouse effect. More heat was trapped on Earth's surface, and the climate became warmer.

Explanation:

the answer for apex is "1 and 6"

the answer is d. chordata