I think the correct answer from the choices listed above is the third option. The barrel of a gun is also known as bore. The barrel is the metal tube which the bullet is fired and the bore is the inside of the barrel. It is the one closest to the barrel so it must be the answer.
        
                    
             
        
        
        
Nuclear power plants use the nuclear fission reaction to release energy and generate electricity through energy conversion. Take the pressurized water reactor nuclear power plant as an example to illustrate its working principle.
In the pressurized water reactor, a large amount of heat is generated by the self-sustaining chain fission reaction of the nuclear fuel nucleus. The coolant (also called the heat carrier) brings the heat in the reactor to the steam generator and transfers the heat to the working medium, water. The main circulation pump then delivers the coolant back to the reactor for recycling, thereby forming a circuit called the first circuit. This process is also the energy conversion process of nuclear fission energy converted into thermal energy.
The working medium on the secondary side of the U-tube outside the steam generator is vaporized by heat to form steam. The steam enters the steam turbine to expand work, and converts the heat energy released by the steam enthalpy into the mechanical energy of the rotor of the steam turbine. This process is called thermal energy conversion to mechanical energy. The energy conversion process. The steam that has done work is condensed into condensed water in the condenser and returned to the steam generator to form another circulation loop called the second loop. This process is called the energy conversion process of converting thermal energy into mechanical energy. The rotating rotor of the steam turbine directly drives the rotor of the generator to rotate, so that the generator emits electric energy, which is an energy conversion process that converts mechanical energy into electrical energy.
 
        
             
        
        
        
#1 the relationship between universes and galaxies is that galaxies are made up of universe. and the relationship between stars and solar systems is every solar system contains at least one star.
#2. galaxies form after several planets form rather close to each other. 
#3. the last one I don't know
        
                    
             
        
        
        
I think it’s increase in gene flow
        
             
        
        
        
<h2>
Hey There!</h2><h2>
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Answer:</h2>
Chloroplasts are found in Eukaryotic Autotrophs i.e. those who can make their own food with the help of sunlight using carbon dioxide and water. Eukaryotes are Eukaryotes are organisms whose cells have a nucleus enclosed within a nuclear envelope.
<h2>_____________________________________</h2><h3>Example:</h3>
The Example of Eukaryotic Autotrophs are Plants and Algae. They are the producers in the food chain also the main source of the oxygen, as they use Carbon Dioxide for a glucose's carbon structure and releases oxygen as By-Product. 
<h2>_____________________________________</h2><h3>Why are they green?</h3>
Chloroplasts get their green color by the presence of chlorophyll, which is the main site for the process of photosynthesis. It is a green photosynthetic pigment found in plants, algae, and cyanobacteria. Chlorophyll absorbs mostly in the blue and all the other colors to the lesser extent while reflecting green. They are present in leaves, and as the chlorophyll reflect green color, Thus the leaves look green to us.
<h2>_____________________________________</h2><h2>Best Regards,</h2><h2>'Borz'</h2><h2 />