The raw materials of photosynthesis, water and carbon dioxide, enter the cells of the leaf, and the products of photosynthesis, sugar and oxygen, leave the leaf.
        
                    
             
        
        
        
Answer:
The answer is "Option A".
Explanation:
The program to the given question can be given as:
program:
var1 = "Happy" #defining variable var1
var2= "Birthday" #defining variable var2
var3 = (var1+var2) *2 #defining variable var3 and calculate value
print (var3) #print value.
Output:
HappyBirthdayHappyBirthday
In the above python program, three variable is defined, that is var1, var2, and var3, in which variable var1 and var2 we assign a value, that is "Happy" and "Birthday".
In variable var3 we add the value of var1 and var2 variable and multiply by 2. It will print the variable value two times. and other options are not correct that can be defined as: 
- In option B and C, Both variable var1 and var2 print there values two times but in option B var1 value print two time and var2 value print one time only and option C var1 variable value is print only one time and var2 variable value is print two times that's why it is not correct.
- In option C, Both variable var1 and var2 print there values two times that's why it is not correct.
 
        
             
        
        
        
for such experiment, you do it with care and to acquire and determine to put experience in it
Explanation:
because without you been or using experience the experiment will not correct
 
        
             
        
        
        
Answer:
Ethernet standards are written and maintained by the IEEE, the Institute of Electrical and Electronic Engineers which has its corporate office in New York City and its operations center in Piscataway, New Jersey.
Explanation: