Teacher: Given a list of steps and an additional step, determine where the step fits into the original list of steps. A correct answer, correctly places the given step into the set of steps so that it creates a new plausible set of steps. Output must be formatted as 'After step n', where n is the step number after which the given additional step is to be inserted.
Teacher: Now, understand the problem? If you are still confused, see the following example:
Steps: (1) Solar radiation reaches Earth's atmosphere (2) Some is reflected back into space (3) The rest of the energy is absorbed by land and oceans, heating the Earth (4) Some of this heat is trapped by greenhouse gases in the atmosphere (5) Human activities such as burning fuel are increasing the amount of greenhouses gases (6) This causes more heat radiation to stay trapped in our atmosphere (7) The Earth's temperature rises  
Where does the following step fit into the given list of steps: Heat radiates from Earth to space 
Solution:  After step 3. 
Reason: The correct answer is 'After step 3'. The given step is 'Heat radiates from Earth to Space'. Step 3 introduces a new concept of generated heat. Step 4 mentions that the heat is trapped into the atmosphere. In order for the heat to get to the atmosphere, the heat must radiate from Earth to space. Therefore, the correct answer is 'After step 3.'

Now, solve this instance: Steps: (1) A plant dies (2) The remains of the plant are buried very fast in sediment (3) The soft parts of the plant decay (4) The hard parts of the plant are replaced with minerals (5) The rock erodes (6) The fossil appears on the surface of the ground.  
Where does the following step fit into the given list of steps: The sediment turns into rock 
Student:
 After step 4. 