The correct option is B Spore formation
Rhizopus is a genus of common saprophytic fungi. Rhizopus reproduce by forming asexual and sexual spores. In asexual reproduction, spores are produced inside a spherical structure, the sporangium. These spores are released out by the bursting of the sporangium. In getting a suitable substratum, the spores germinate and form new individuals. In sexual reproduction, a dark zygospore is produced at the point where two compatible mycelia fuse.
Thus, the correct answer is option B, 'Spore formation'.