In what case would forceps be the only option to deliver baby? ie; c-section not an option. does such a situation even arise?

Uncommon but: If the baby is at +3 station meaning it is right at the opening , almost out and the ht rate would go down and stay down, there may not be enough time to go back and do an emergency c- section so an outlet forceps or vacuum delivery would be a much better option and almost every OB knows how to do that with either the forceps or vacuum and outlet delivery is the easiest and safest to , I do those.