Answer: The correct answer is- B) Ecosystem.
Ecosystem can be described as a group of living organisms present in a particular area that are interacting with each other as well as the non living components of that environment. 
In other words, it is the interaction between biotic ( living such as plants and animals) and abiotic ( non living such as temperature, air, water) components of an environment.
Example- Pond ecosystem, lake ecosystem. 
 
        
                    
             
        
        
        
The answer is C. A theory is an idea intended to explain why something happened. It may have not been proven correct e.g. Darwin's theory of evolution
        
             
        
        
        
Explanation:
D) 75 J
Energy is neither related nor destroyed- it's simply converted to different forms. Forces are vectors with both mass and acceleration; they are interactions that have the ability to change an object's motion. As objects move, their potential energy (apprx 100 J) is converted to kinetic energy. However, friction a resistive force, which is formed from the conversion of an object's kinetic energy into heat energy, as two surfaces move along each other.
With the reduction of friction, the energy output should increase, as less energy is lost as heat. Thus, the output should be 75 J. 
Learn more about energy flow at brainly.com/question/6966886
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The training that Michael need to work as a veterinarian in a zoo is to acquire a degree in veterinary medicine.
<h3>Who is a veterinarian?</h3>
A veterinarian is a professional that has passed through a training institution for the purpose of being trained in the area of animal health.
There are different fields in veterinary medicine which Include the following:
- Companion Animal Veterinarians.
- Veterinary Practitioners. 
- Food Animal Veterinarians. 
- Food Safety and Inspection Veterinarians. 
Learn more about veterinary here:
brainly.com/question/7982337
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That a C an dormant volcano