In these questions, the letters are linked in some way. Identify the relation and complete the last box. \[\text{125}\,\,\,\text{:}\,\,\,\,\text{100}\] \[\text{100}\,\,\,\text{:}\,\,\,\,\text{75}\] \[\text{25}\,\,\,\text{:}\,\,\,\,\text{?}\]

• A.  0                            
• B.         50         
• C.  75                         
• D.         100