Depends on what you’re going for. i’d say aquifers. but you can drink from clean rivers
I don’t know the answer either
Answer:
24 is the answer of this question
Answer : The value of diffusion coefficient is, 
Explanation :
Formula used :

where,
D = diffusion coefficient = ?
= 
= 
R = gas constant = 8.314 J/mol.K
T = temperature = 
Now put all the given values in the above formula, we get:


Thus, the value of diffusion coefficient is, 
Out of those ones, im sure its c. It's definitely not b or d. It allows motion but also protects vital organs. :)