How did you handle your most challenging experience in your previous job
If you are a fresher with no work experience or does not have any challenging experience, talk to your seniors or people who has experience. They may give you some examples.
Think of a stressfull thing that happened at your last job. Then write a short description of what it was and what you did. Did you work to resolve the problem? Did you remove yourself from the problem and let other handle it? Stuff like that. Just a short explaination of what happened.
This is more related to problem solving, first, think of a problem you had in you work and what is the action/ solution you have taken to resolve. It is always better to explain the point in logical order with a good example.
When answering a question like this, you should always try and remember two things:
use an example.
use the word 'teamwork'.
Employers want to know how you handle stress, how you worked through that problem, and if you're a team player.