Answer: a.  decreases the present and future risk to human properties
Explanation:
Properties along the coasts can be in danger when high tides come in. This can however be mitigated by walls protecting those properties as it would take a significantly high tide (flood proportion) to scale those walls and come in and damage the property. 
These walls therefore not only decrease the present risk to human properties but if maintained, decrease the future risks as well. 
 
        
                    
             
        
        
        
I wish I could help but I can I’m sorry so good night
        
             
        
        
        
The correct answer is b: cattle on rangeland. A point source of pollution occurs from a single identifiable and usually spatially narrow source. These sources of pollution are usually relatively easily to quantify and manage. In contrast, a non-point source of pollution, such as cattle on rangeland or irrigated agriculture, is variable on both spatial and temporal scales. These sources of pollution are difficult to quantify and manage.