Haploid cells are sex cells or gametes.
        
             
        
        
        
Answer:
C. At least five mass-extinction events have occurred during the last 500 million years.
Explanation:
- The history of mass extinct is related to the five mass extinctions that are caused over by the 350 million years n which many species have disappeared in there short geologic time.
- A massive extinction is caused in the Permian Triassic extinction event i.e about 250 mn years ago which on an estimate has killed 90% of the species.
- The Cretaceous–Paleogene extinction event that occurred over 66 million years ago is known to have wiped out the dinosaurs and many other species.  
 
        
             
        
        
        
Phosphorus is a basic supplement for plants and creatures as particles PO43-and HPO42-. It is a piece of DNA-particles, of atoms that store vitality (ATP and ADP) and of fats of cell films. Phosphorus is likewise a building piece of specific parts of the human and creature body, for example, the bones and teeth. 
Supplements travel through the biological system in biogeochemical cycles. A biogeochemical cycle is a circuit/pathway by which a concoction component travels through the biotic and the abiotic elements of a biological community. It is comprehensive of the biotic factors, or living beings, rocks, air, water, and chemicals.
        
                    
             
        
        
        
Sugar-phosphates and nucleotides
        
             
        
        
        
The correct answer is option C, that is, the presence of the nuclear membrane.  
Cyanobacteria is a phylum of bacteria that attain their energy via the process of photosynthesis, and are the only photosynthetic prokaryotes possessing the tendency to generate oxygen. As a prokaryote, they are devoid of the nuclear membrane.  
Euglena refers to a single cell flagellate eukaryote. It comes under the class Euglenoidea. The species of Euglena are witnessed in salt water and in freshwater. Being a eukaryote, they possess nuclear membrane.