What are the different actions I can take when a Rate Limit is exceeded in Cloudflare?

Cloudflare offers several actions: 'Block' immediately blocks the request; 'Challenge (Managed Challenge)' presents a JavaScript challenge to verify the user is legitimate; 'Challenge (CAPTCHA)' requires the user to solve a CAPTCHA; 'Log' simply logs the event without taking action; and 'Allow' (which effectively disables the rule for that match).