All of the following are good reasons for an applied econometrician to learn some econometric ...

All of the following are good reasons for an applied econometrician to learn some econometric theory, with the exception of
 
  A) turning your statistical software from a black box into a flexible toolkit from which you are able to select the right tool for a given job.
  B) understanding econometric theory lets you appreciate why these tools work and what assumptions are required for each tool to work properly.
  C) learning how to invert a 44 matrix by hand.
  D) helping you recognize when a tool will not work well in an application and when it is time for you to look for a different econometric approach.