That would have to be the large continent of Africa! Hope this helps :)
        
             
        
        
        
for better research go to under NOAA - Climate.gov
This is a short paraphrased summary of the article about ice cores in that website.  
Answer: Researchers in labs may melt or crush bits of the ice core a little at a time, each deeper layer shows the time in the Earth's climate history. Tiny pieces of pollution, metals, radoiactive fallout, pebbles, sea salt, volcanic ash and even air bubbles all present important information that researchers can look for to track changes in the atmosphere's composition and temperature. 
 
        
             
        
        
        
The correct answer is B Subduction. Subduction is the process by which an oceanic plate gets dragged under another plate and is eventually destroyed in the mantle. Subduction occurs at convergent margins where two oceanic plates collide or an oceanic and Continental plate collide. Oceanic crust is made of mainly of silica and magnesium which is heavier or denser than continental crust which is composed mainly of silica and aluminium. 
The subducting plate melts producing excess magma giving rise to volcanoes along these margins. 
        
             
        
        
        
1. The protection granted by a nation to someone who has left their native country as a political refugee. 
2. An institution offering shelter and support to people who are mentally ill