So in order to solve this problem, follow the following steps:
1. Go to adsense.com, click on fix now and on download button.
2. Open the downloaded ads.txt file. Copy the whole code.
3. Go to blogger.com, click on Settings -> Search preferences -> Monetization -> enable custom ads.txt and paste the copied code in the box and save changes.
4. It might take upto 24 hours to review.