Judith Jarvis Thomson: Turning the Trolley

Judith Jarvis Thomson: Turning the Trolley
The "trolley problem" arises when we attempt to reconcile our intuitive moral judgments concerning two imaginary cases. On the one hand, it seems permissible for a bystander to pull a switch, turning a runaway trolley off of a track on which it will kill five innocent people, and onto a track on which it will kill one innocent person. On the other hand, it seems morally wrong for the bystander to push a fat man into the path of an oncoming trolley to stop the trolley and prevent it from killing five innocent people. These two verdicts seem puzzling because in each case the agent has the option of choosing the death of one person over the death of five, yet doing so seems permissible in the first case but not the second. Philippa Foot proposed two principles to deal with cases of this sort. The first principle holds that A must let five die if saving them requires killing B, and the second holds that A must not kill five if he can instead kill one. Foot's first principle is widely regarded as counterintuitive, because it implies that it would be wrong for the bystander to turn the trolley onto the less-populated track.
Thomson argues that Foot's two principles are in fact correct, and that it is impermissible to turn the trolley in the first case. She argues for this position by presenting a variation on the first case. Suppose that the bystander has three options: He can let the five die, turn the trolley so that it kills one other person, or turn the trolley in a different direction so that it will run over him. Thomson claims that the bystander may not permissibly turn the trolley onto the other innocent person; to do so would be to require a third party to bear the cost of his good deed. Thomson then argues that the same prohibition holds even when there is no option for the bystander to turn the trolley in his own direction. Thomson therefore concludes that turning the trolley is impermissible.
-Foot claimed that negative duties:

A) are the only kinds of duties that we have.
B) are less weighty than positive duties.
C) are exactly as weighty as positive duties.
D) are weightier than positive duties.