Q: 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.
Steps: (1) Animals and plants die in soft soil or mud (2) Sediment builds up over the remains (3) The remains decompose, leaving only trace amounts (4) A fossil is formed  
Where does the following step fit into the given list of steps: The remaining parts over the years are replaced with mineral 
A:
 After step 3. 