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a)                                                                   
==========================================================================

                      +-----------+                                      
                      | Telephone |                                      
                      +-----------+                                      
                            |                                            
                            |                                            
    +------------>-------->-+-----<---------<-------+                    
    |                |               |              |                    
+-------+	+---------+	        +--------+    +---------+                
| Cable |->-| Handset |	        | Dialer |    | Housing |                
+-------+	+---------+	        +--------+    +---------+                
                |                    |              |                    
       +-->-----+--<-+               |              +---------------+    
       |             |               |              |               |    
+-----------+    +----------+    +--------+      +---------+    +-------+
| Moutpiece |    | Earpiece |    | Button |      | Chassis |    | Shell |
+-----------+    +----------+    +--------+      +---------+    +-------+

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b)
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In file included from Handset.hh:7,
                 from Telephone.hh:7:
Cable.hh:4:7: fout: redefinition of ‘class Cable’
    4 | class Cable {
      |       ^~~~~
In file included from Telephone.hh:4:
Cable.hh:4:7: note: previous definition of ‘class Cable’
    4 | class Cable {
      |       ^~~~~

Header protectors missing in Cable.hh

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e)
==========================================================================
Yes, it does.