The trolley problem is a series of thought experiments that should be morally equivalent. In all variations, the reader can choose to take an action that will directly result in the death of an innocent person who was otherwise ‘safe’, or do nothing and allow a larger group of people to die, and ask what is the morally correct choice.
There’s no right answer to the trolley problem. The interesting take away is that what most people agree is the morally correct answer depends how the problem is framed.
When the situation is framed as “you’re deciding between one person dying and many people dying” most people will agree the morally correct choice is the one where the fewest people die.
But when the situation is framed as “are you justified in murdering an innocent person to save many” most people agree the morally correct answer is no.
There’s even one variation where is is considered by most morally correct to murder one person to save many, if the person you’re murdering is responsible for putting the larger group in harms way in the first place.