The correct answer is A. PQSR.
The sentence is about a pet dog who would never sleep anywhere except on the sofa. The first clause, “It was true that,” introduces the main idea of the sentence. The second clause, “the pet dog would never sleep anywhere,” provides more information about the dog. The third clause, “we once had,” provides more information about the setting. The fourth clause, “except on the sofa,” provides the final piece of information about the dog’s sleeping habits.
The other options are incorrect because they do not follow the correct sequence of events. Option B, PRQS, puts the third clause before the second clause. This is incorrect because the third clause provides information about the setting, which should come after the information about the dog. Option C, RPQS, puts the fourth clause before the second clause. This is incorrect because the fourth clause provides information about the dog’s sleeping habits, which should come after the information about the dog. Option D, SPQR, puts the first clause after the second clause. This is incorrect because the first clause introduces the main idea of the sentence, which should come first.