Answer :
The question is asking to states the reason why the heat travels to the iron to the shirt and base on my research, I think that the best reason to it is due to the heat transfer from one object to another that could allow the both of them have and equilibrium between their temperatures. I hope you are satisfied with my answer
Explanation
The Iron is incontact with the shirt. So, heat is transferred from the iron to the shirt because they are in contact.
Before the contact, there is temperature difference between the shirt and the iron. When they come into contact there must be exchange of heat energy, this happens until equilibrium state is reach.
