The one that is least likely to increase the rate of diffusion would be : small concentration of gradient
The rate of diffusion will more likely to increase if : 
- the concentration gradient is greater
- distance is decreased
- The surface Area is increased
hope this helps
        
             
        
        
        
Related to living organisms
the biotics requlating of the environment is a key to global change
        
             
        
        
        
If a HYPOTHESIS is wrong scientists come up with a conclusion, the hypothesis doesn't matter for the result. It is just an educated guess based on the results they expect our hope the achieve.