Under the Basel Advanced IRB (Internal Ratings-Based) approach, the asset correlation parameter for residential mortgages is set at 15%, whereas for qualifying revolving retail exposures (QRRE), it is 4%. Thus, residential mortgages have a higher asset correlation. Options A and B are incorrect as banks are permitted to use either the standardized or the IRB approach for retail exposures depending on regulatory approval. Option C is incorrect because under the standardized approach, regulatory retail exposures typically receive a 75% risk weight, while residential mortgages generally receive a 35% risk weight.