what is the saddest episode of supernatural?
['3 Dark Dynasty (10.21)', '4 Do You Believe in Miracles (09.23) ... ', '5 Sacrifice (08.23) ... ', "6 Death's Door (07.10) ... ", '7 Swan Song (05.22) ... ', '8 Dark Side of the Moon (05.16) ... ', '9 All Hell Breaks Loose (02.21) ... ', '10 In My Time of Dying (02.01) ... ']