I. Mt. Rainier - (D) USA: Mt. Rainier is located in the state of Washington in the United States, so the correct country match is USA.

II. Etna - (A) Italy: Mt. Etna is located on the east coast of Sicily in Italy. It is one of the most active volcanoes in the world, and Italy is the correct country match.

III. Paricutin - (B) Mexico: Paricutin is a volcano located in the state of Michoacan in Mexico. It is known for its sudden emergence in 1943 and subsequent volcanic activity.

IV. Taal - (C) Philippines: Taal Volcano is located on the island of Luzon in the Philippines. It is one of the most active volcanoes in the country.

So, the correct matching is:

I. Mt. Rainier - (D) USA

II. Etna - (A) Italy

III. Paricutin - (B) Mexico

IV. Taal - (C) Philippines

Therefore, the correct answer is:

I-D, II-A, III-B, IV-C