I think is D Carbon dioxide 
PLEASE MARK ME AS BRAINLIEST 
 
        
             
        
        
        
Because our brains are the most developed out of all of the other species on this planet. Also, we require the most maintenance to survive. We can’t live in the ocean, such as a fish, shark, dolphin, etc. but we also can’t live in the forest such as bears, deer, coyotes, etc. we need to live in a stable environment when we will have enough food to survive as well to live in certain temperatures that are best suited for our kind. Hopefully that helped a little bit
        
             
        
        
        
Answer:
This is the rock cycle I believe hope this helps
 
        
             
        
        
        
Answer:
by hiding and never getting seen and staying cautious
Explanation:
 
        
             
        
        
        
The correct answer is B. Ordovician period
Explanation:
Plants are mainly multicellular organism that depends mainly on photosynthesis to obtain energy, this includes a wide variety of species such as grass, flowering plants, trees, shrubs, etc. Additionally, plants are considered as one f the two major divisions or kingdoms along with animals. In terms of history, it has been determined first land plants appear during the mid-Ordovician period around 470 million ago, although organisms that were the origin of land plants developed in water in previous periods, also by the Devonian period a wide variety of plants have emerged with features that are still part of plants nowadays. Therefore, plant life first appeared on land during the Ordovician period.