Which of the following processes is a form of sexual reproduction?

Among the given options, "Conjugation in Spirogyra" is a form of sexual reproduction. Conjugation is a process where two haploid individuals (gametes) of Spirogyra, a filamentous green algae, come together and fuse their cytoplasmic contents, followed by the fusion of their nuclei to form a zygote. The zygote then undergoes meiosis to form haploid spores which germinate to form new filaments. On the other hand, the other options are forms of asexual reproduction. Budding in yeast is a process where a new individual grows out of the parent cell. Binary fission in Amoeba is a process where the parent cell divides into two identical daughter cells. Rhizome production in ginger is a vegetative reproduction where a new plant is formed from an underground stem of the parent plant without the involvement of gametes.