If using Mobile Web (not the App), click HERE.
When you click the checkbox next to "I'm not a robot" sometimes it will become a green check mark after a moment of thinking and sometimes a selection of images are shown and they ask for you to click all of the pictures with a particular thing. This is image recognition and is quite easy for humans and almost impossible for machines, but you have to click on all of the images that match the word and none of the images that don't.
In the example below: is says to tells you to select all of the food, so you would only click the burger, the sandwich, and the cake, but none of the others. The click "Verify".
If you do not see the pop-up asking you to show that you're not a robot and the box remains unchecked, you should refresh your page and try again.
If refreshing your page didn’t work, it’s time to send the support team a message letting them know about the problem. You can do this by clicking the Report a Problem button located at the bottom of the CAPTCHA window.
Then you can select Low Quality Image or No Valid Solution and then click the Report Captcha button above that.