Final answer:
The spore-producing structure in Rhizopus is a sporangium, which is responsible for the asexual production of spores and their dispersion by wind.
Step-by-step explanation:
The spore-producing structure in Rhizopus is called a sporangium. This structure is responsible for the production of numerous asexual spores. The sporangium grows at the end of a stalk-like structure known as a sporangiophore, which elevates the spores to facilitate their dispersal by wind. Therefore, the correct answer is B) sporangium. This is different from mushrooms, which have a spore-producing structure called a basidiocarp (the fruiting body), where spores are produced in specialized cells called basidia. Rhizopus is a type of fungus that exhibits both asexual and sexual forms of reproduction, with the sporangium being a key feature in its asexual cycle.