The goal of your answer is to showcase in-depth knowledge of Photoshop and explain how you use it as an extension of shooting images in the field. The interviewer expects you to be knowledgeable of the tools you will use on the job.

Focus on the tools you would use in Photoshop to deal with an image that is soft. Make sure you tie it back to photography and explain the reasons you might use HDR.

HDR stands for "high dynamic range." To create an HDR effect, you essentially stack several layers of an image. Each layer has different exposure settings. When you combine them, you get a composite image that can be rich in color and detail. Enhancing an image of a landscape is a great use of HDR. When you are in the field, you'd take multiple shots on a tripod with a variety of exposures and then stack them as layers in Photoshop or Lightroom. By doing this, you can pull more color out of an overexposed sky, lighten shadows on the ground, and enhance contrast and color. You have to be conservative in your adjustments if you want a subtle boost or pop of a landscape. If you use it heavily, an image will start to look surreal.