Option 1 is correct, stating that both A (Chile continues to be an important producer of copper in the world) and R (Chile is endowed with the world’s largest deposit of porphyry copper) are true, and R explains A. This is due to the fact that Chile being a significant producer of copper is directly related to the existence of the world`s largest deposit of porphyry copper in this country.

Option 2 would be correct if both statements are correct, but the large porphyry copper deposit in Chile does not explain why Chile is an important copper producer.

Option 3 would be correct if Chile was a significant copper producer but did not have the largest deposit of porphyry copper.

Option 4 would apply if Chile was not a significant copper producer, however, it had the largest deposit of porphyry copper. But this is incorrect, Chile is both a major producer and has large deposits.