Answer:
I think A. is the right answer. 
Explanation:
I searched up on how to determine population size and here here are some things I found. ¨The number of individuals in a specific area¨, ¨The most obvious way to determine the size of a population is to count, one by one.¨, but one thing I´m kinda sure is right is this one. It´s determining population size.  ¨Some methods of determining the size of population are direct and indirect observations, sampling, and mark-and-recapture studies¨ But just see for yourself.
 
        
             
        
        
        
Answer:
B
Explanation:
The closer the light source the higher the amount of Oxygen gas. 
Reasoning: Plants give off oxygen and according to the data the closer the light it the more bubbles there are. :)
 
        
             
        
        
        
Answer:
I think it's climate, if I'm not mistaken. 
 
        
             
        
        
        
Answer: karyotype
Explanation: if you suspect trisomy, you need to count chromosomes!
 
        
             
        
        
        
Answer:
primary waves
<em>Hope</em><em> this</em><em> helps</em><em> </em><em>:</em><em>)</em>