The plants that were allowed to self pollinate were the F1 plants. 
The plants that are true breeding are P generation plants. 
The plants where there were 3times as many tall plants as short plants are in F2 generation. 
<h3><u>Explanation:</u></h3>
This question is based on the Mendel’s Experiment. Sir Gregor Johann Mendel was the father of genetics who experimented on garden pea plants <em>Pisum</em> <em>sativum</em> to see whether the characters got mixed or not and to know the real cause behind different traits of same character in plants. 
He took the pure homozygous tall and short plants separately which he called as parental generation or P generation. These plants were homozygous, hence pure breeding. 
As these plants were crossed between themselves, then the F1 generation showed all tall plants. This is because of the heterozygous plants which showed character of dominant trait. These plants were allowed to self pollinate. 
As a result of self pollination of the F1 plants, the F2 plants were 75% tall in number whereas the other 25% short, which gave the phenotypic ratio of 3:1.
 
        
                    
             
        
        
        
Types of thermal is Radition conduction and convection in that order
Top is no particles, vibrating in place, moving freely 
If that’s wrong with the vibrating and moving freely
        
                    
             
        
        
        
The correct option is A.
The serosa refers to the outermost layer of loose connective tissues which is often covered by mucus and which contains blood vessels. In the gastrol intestinal tract, the serosa refers to the outermost layer of the wall of the GI tract. One major function of serosa is to reduce friction from muscle movement.