In the following passage, some of the words have been left out. Read the passage carefully and select the correct answer for the given blank out of the four alternatives.
"Jim Crow" shuns the mountains for reasons satisfactory to himself; not so the magpie, the raven, and __________ mischief-maker, Clark's nutcracker. All of which keeps the bird-lover from the East in an ecstasy of surprises until he has _____________ accustomed to his changed environment. One cannot help ___________ into the speculative mood in view of the sharp contrasts ______________ the birds of the East and _________ of the West.
until he has _____________ accustomed to his changed environment