Visitors to our country treat us as we are unintelligent because we are underdeveloped. Especially if we express opinions they do not agree with.
They must learn that people from countries who's economies are lessly developed are not necessarily less intelligent.
Our economies will change over time.
Especially if the visitors' country's stopping unfair trade practices.

Sentence 2 of the passage...
a. contains a sentence fragment.
b. changes point of view from "we" to "he".
c. ends with the prepositional adjective "agree with".
d. incorrectly uses the subject form of the pronoun "they" instead of the object form.