a) 1) the Rocky Mountains (mountain ranges require "the" while individual peaks don't (the Alps, the Andes etc but Mount Everest, Mont Blanc etc) 2) the Cavern club (I googled this up; clubs may or may not require "the") 3) the right man (if you picture a man who is the perfect/best candidate for the job then you'd say "the right man". "A right man" would mean there are many men suitable for the job but obviously that wasn't the intention of the speaker). 4) the brightest (superlative) b) 1) I wonder if he will come.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.