Answer:
Option A. are mostly non-metals. 
Explanation:
Oxidising agents are mostly non-metals because non metals gains electron from the metal during chemical bond and we know that oxidising agent is electron accepter not donar. For example, Sodium is a metal react with chlorine which is a non-metal so the sodium losses electron and this electron is gain by chlorine atom forming sodium chloride. In this example chlorine is a non-metal which gains electron. 
 
        
             
        
        
        
Answer:
SA Node
Inter-nodal Pathways
AV Node
AV Bundle
Bundle Branches
Purkinje Fibers
The SA nodes functions first for setting pace for the heart, then the inter-nodal pathway make link b/w SA and AV node. AV node is site of delay when contraction of atria occurs. AV bundle is the mean of electrical link b/w atria and ventricle. The conveying of impulse to the inter-ventricular septum occurs through bundle branches, while conveying of impulse throughout and along the walls of ventricle occurs through Purkinje fibers. 
 
        
             
        
        
        
D) a change in protein synthesis
        
                    
             
        
        
        
Answer:
Sun
Explanation:
The main source of energy of energy for most organisms and the ecosystems. For example, producers, such as flowers and trees, use sunlight to go through photosynthesis.
 
        
             
        
        
        
The main function of the mitochondria is respiration in the cell. To produce energy from broken down organic molecules. (i.e. carbohydrates.)