How can HR measure its effectiveness and/or impact in the learning and development function?

Assignment Requirements:
Create a presentation (e.g. PowerPoint or Keynote slides) that clearly explains the following:
How can HR measure its effectiveness and/or impact in the talent acquisition process?
How can HR measure its effectiveness and/or impact in the learning and development function?
How can HR measure its effectiveness and/or impact in the area of compensation and benefits?
How can HR measure its effectiveness and/or impact in employee engagement and retention?