Which of the following sentences is grammatically correct?

is the answer C ?
a. They have relatives in Albania. Which is in southern Europe.
b. They have relatives. In Albania which is in southern Europe.
c. They have relatives in Albania, which is in southern Europe.
d. They have relatives in Albania; which is in southern Europe.

The correct answer is c. "They have relatives in Albania, which is in southern Europe."

To determine the correct answer, you need to look for the sentence that properly uses punctuation and has the appropriate placement of the phrase "which is in southern Europe."

Option a: "They have relatives in Albania. Which is in southern Europe." The phrase "Which is in southern Europe" should be connected to the previous sentence with a comma or a semicolon.

Option b: "They have relatives. In Albania which is in southern Europe." This sentence separates the phrase "which is in southern Europe" from the preceding sentence, which creates a disjointed structure.

Option c: "They have relatives in Albania, which is in southern Europe." This sentence correctly uses a comma to link the phrase "which is in southern Europe" to the previous sentence, providing necessary information about the location of Albania.

Option d: "They have relatives in Albania; which is in southern Europe." Though the semicolon is used correctly to join two related independent clauses, the word "which" should be preceded by a comma when used as a nonrestrictive relative pronoun.

Therefore, sentence option c is grammatically correct.