the third one,

The Last Supper

     Besides the 'Mona Lisa' , this painting 'the Last supper' was also well-known of DA VINCI 's masterpiece.  It  was about JESUS and HIS disciples had the last supper ,because JESUS was going to die soon. I have seen this painting in the Louve before. it was one of the biggest paintings being displayed in the Louve.
i think it 's a difficult drawing, because each person had different faces and motions. However , DA Vinci could express them clearly.
 
 

More  about the 'the Last supper'
http://www.mystudios.com/gallery/giotto/28a.html