Answer to Question m19
    
    
    
    Incorrect. Suppose A = [1,3,5] and
    B = [2,4,6].  The third case computes
    C = [1], which is ignored.  It returns
    merge([3,5], [2,4,6]).  If the recursive
    call is correct, that is [2,3,4,5,6].
    The head of A has been thrown away
    by adding it to list C, which is ignored.