In these questions, the letters are linked in some way. Identify the relation and complete the last box. \[\text{A}\,\,\,\text{:}\,\,\,\,\text{Z}\] \[\text{B}\,\,\,\text{:}\,\,\,\,\text{Y}\] \[\text{C}\,\,\,\text{:}\,\,\,\,\text{X}\] \[\text{F}\,\,\,\text{:}\,\,\,\,?\]

• A.  V           
• B.         S       
• C.  U                           
• D.  Q