Can you choose the right spelling for each poem line?

So that's the end of Betty, but you needn't be (upset, upsett, upsset)

unless you meet a yeti in the (montains, mountains, mountins) of Tibet.

Then just stay calm and (steddy, stedy, steady).

Don't be (nervous, nervus, nervos). Don't you fret. And don't cook him spaghetti or, who knows what you might get?