C

Test question analysis: Yeast reproduces by budding, that is, budding is the most common reproduction method of yeast. Under good nutritional and growth conditions Under the condition, yeast grows rapidly. At this time, you can see buds growing on all cells, and new buds can be formed on the buds, so you can often see clusters of cells, starting from the mother cells. A bud grows, gradually grows to a mature size and then separates from the mother. When the nutritional status is not good, some yeasts that can reproduce sexually will form spores (usually four), which will germinate when the conditions are suitable; bacteria simply carry out Fission reproduction. One bacterium splits horizontally into two bacteria. This method of reproduction is called fission. When the environment is suitable, bacteria can divide once in less than half an hour. It can be seen that the reproduction speed of bacteria is quite fast. Choose C. .