Which direction do you choose?
If you chose to save the five people, what if the track you chose had two or three loved ones? If you chose to saved the loved one, what if the number of people that you had to run over in order to save him/her was 10 or 20?
****also no witty loopholes please, you cannot derail or stop the train to avoid the situation. You are in control of the direction, not the engine/track. Everyone is tied down in such a way that they will die if you choose their direction. You also cannot avoid responsibility by letting the train 'run its course'.