Compiling and Linking GTK 3 with C project on Ubuntu
===

I believe this is not a duplicate question, I have seen all questions/answers before I post this question. I think I have a different situation here.

I use Ubuntu 12.04 and downloaded **GTK 2 and 3**. I have copied a simple GTK source code from GNOME's website. But when I use this  command in terminal:

    gcc `pkg-config --cflags --libs gtk+-3.0`  hello.c -o hello
    
I get this:

    hello.c:(.text+0x17): undefined reference to `gtk_init'
    hello.c:(.text+0x23): undefined reference to `gtk_window_new'
    hello.c:(.text+0x47): undefined reference to `gtk_main_quit'
    hello.c:(.text+0x5b): undefined reference to `g_signal_connect_data'
    hello.c:(.text+0x67): undefined reference to `gtk_widget_show'
    hello.c:(.text+0x6c): undefined reference to `gtk_main'

here is my code:

    #include <gtk/gtk.h>
    
    int
    main (int   argc,
    char *argv[])
    {
      GtkWidget *window;
    
      gtk_init (&argc, &argv);
    
      window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
    
      g_signal_connect (window, "destroy", G_CALLBACK (gtk_main_quit), NULL);
    
      gtk_widget_show (window);
    
      gtk_main ();
    
      return 0;
    }

I'm not sure if errors appear because I have two versions of GTK+ or what.
I'm extremely newbie in Applications Development in Ubutnu/Linux.