The mold responsible for the distinctive blue marbling seen in blue-veined cheeses, such as Roquefort, Gorgonzola, and Stilton, is Penicillium roqueforti. This mold is intentionally introduced during the cheese-making process and is allowed to grow inside the cheese, producing the characteristic blue veins.
Penicillium roqueforti contributes not only to the blue coloration but also to the strong, tangy flavor profile of blue cheeses. It breaks down fats and proteins in the cheese, which enhances its flavor and texture.
On the other hand, Penicillium camemberti (option D) is used in the production of soft cheeses like Camembert, giving them their white rind, but it does not contribute to the blue marbling. Rhizopus oryzae (option A) and Aspergillus niger (option C) are molds that are used in other types of fermentation but are not responsible for the blue veins in cheeses.
Thus, the correct answer is (B) Penicillium roqueforti.