Answer:
I guess it might be d 
if I am right mark it as brainliest pls
 
        
             
        
        
        
The effect of greenhouse gases on the Tundra ecosystem will cause Increased greenhouse gases will increase the overall average temperature of the region, resulting in the melting of the polar ice.
The tundra is a scientific term to refer to the polar geographic region characterized by:
- Low growing vegetation.
- Frozen subfloor.
- Absence of arboreal vegetation.
- Soils that are covered in moss, lichens, snow, or ice.
- In some places they are swampy.
This region is being affected by greenhouse gases because they heat the poles, cause a thaw, and the water level is rising making the tundra an exclusively marshy region.
Learn more in: brainly.com/question/2018762
 
        
             
        
        
        
The sit down strike changed the United Automobile Workers from a collection of isolated locals on the frill of the industry, into a major labor union. Leading to the unionization of the domestic United States automobile industry.
        
                    
             
        
        
        
Spain and the United States i think