A copper block (20°C) is placed in contact with a lead block (30°C), which is already in contact with an iron block (70°C). What will happen in this situation?

Heat will flow from the iron to the lead and from the lead to the copper until the temperatures are equal.

Heat will flow from the copper to the lead and from the iron to the lead until the temperatures are equal.

Heat will flow from the copper to the lead to the iron until the temperatures are equal.

Heat will flow from the lead to the copper and to the iron until the temperatures are equal.