Answer:
You say there is one twin. Twins, when referred to as a set, require an s, just like most other groups of objects. There are the twins.
 
        
             
        
        
        
The answer is C. Works Cited
        
             
        
        
        
Answer:
I took a summer program in the summer where many people there were immigrants allowing for us the learn a new language as the summer went by and use it everyday