The correct answer is option C, that is, have a wider range of environments.  
It has been known that geographic isolation is a general way for the initiation of the process of speciation, like the rise of mountains, rivers changing course, migration of organisms, continental drift, due to this what was once a steady population gets differentiated into two or more kinds of smaller populations.  
A mountain range, due to distinctions in temperature and precipitation as a result of different altitudes, can lead to a higher rate of speciation. Due to these differences, a single mountain range can exhibit an enormous array of biodiversity and climate zones.
 
        
             
        
        
        
I think D is the right answer.
        
             
        
        
        
Why temperature affects heart rate in ectothermic organisms? If the temperature is within the optimal range for enzyme activity more ATP will be produced and the heart will beat faster due to increased metabolic activity and energy availability.
        
             
        
        
        
A cladogram is similar to Family Tree  
Explanation:
A cladogram and a family tree both show relationships between common ancestors. It shows the relationship the organism but it is not same as evolutionary or family tree because it doesn’t show the relationship with ancestor to their descendent and also it doesn’t show how they changed. 
Cladogram is type of diagram based result analysis. Clade is group of organism with their last similar ancestor. A cladogram is represented through lines.