We need a grammatically correct and logically coherent phrase that continues smoothly from the relative pronoun "who."
- Option (A) uses “realize their country,” which is awkward and unidiomatic English. One does not “realize” a country; the verb is mismatched.
- Option (B) uses “are not realizing,” which is incorrect as “realize” is a stative verb and not normally used in the progressive tense.
- Option (C) is the best and most natural phrasing. It uses the correct verb tense (“do not seem to realize”) and flows smoothly, ending with “learn from it” which correctly refers to “their own country.”
- Option (D) is incomplete; it ends abruptly at “learn from,” leaving the object of the preposition undefined.
Therefore, option \(\boxed{\text{C}}\) is the most grammatically and logically accurate substitute.