Which of the following is not a type of vaccine? 

Inactivated, live attenuated, and subunit vaccines are all types of vaccines that are designed to stimulate the immune system to recognize and defend against specific infectious agents, such as viruses or bacteria.

Homeopathy is not a type of vaccine. It is a form of alternative medicine that involves the use of highly diluted substances to treat various health conditions. Homeopathic remedies are prepared by repeatedly diluting a substance in water or alcohol and then shaking it vigorously, a process called succussion. The resulting solution is then further diluted and succussed several times until the desired dilution is achieved. According to the principles of homeopathy, the more diluted the remedy, the more potent its healing properties. However, there is no scientific evidence to support the effectiveness of homeopathy in preventing or treating infectious diseases.