<span>Mesozoic Era is the anwser</span>
        
             
        
        
        
The answer is B. Geology has shown a thin layer of iridium (a rare mineral on earth but found on asteroids and meteors) in the rock layers between the Cretaceous and Paleogene periods. Below this layer are numerous fossils of  pterosaurs and dinosaurs, but above the layer are drastically few. The aftermath of asteroid impact is believed to have smothered most vegetation from earth which dinosaurs depended on as a source of food.  
 
        
                    
             
        
        
        
Answer:
environmental factors do not affect a species
 
        
             
        
        
        
When the bread and butter is in mouth, mechanical digestion starts. The size of the food gets reduced and it mixes with saliva for easy swallowing. The salivary amylase in saliva begins the digestion of starch in the bread. This is the start of chemical digestion. When the undigested bread and butter reached the stomach, lower esophageal sphincter relaxes and allow the chewed food to enter. The gastric secretions containing HCl, acts on the undigested food to produce chime. HCl kill the microorganism on the food and also denatures the protein and later attacked by digestive enzyme pepsin. Pepsin breakdown protein in the bread, butter . Later on gastric lipase begins to digest fat present in butter. Digestion of the starch in bread does not occur in the stomach because the salivary amylase that began chemical digestion in mouth became inactive in the presence of HCl. Further the chime enters the small intestine where bile secreted by the gall bladder emulsifies the fat and break into small globule which helps in fat absorption. 
 
        
             
        
        
        
The answer is A. This ensures that the resource has enough time to regenerate so as to sustain consumption. An example is that of the carrying capacity of a habitat. If a herd of cows exceed the carrying capacity of the  grazeland, the grass will be depleted and the area will be predisposed to desertification. The environment will not be able to sustain the cows anymore until the herd number reduce.