Which process is specifically caused by bacterial action during decomposition?

Putrefaction is the specific process caused by bacterial action during decomposition. This process involves the breakdown of proteins and other organic matter by microorganisms, particularly bacteria, which leads to the production of various gases and compounds. It is during putrefaction that the characteristic odors associated with decay arise, resulting from the release of substances like hydrogen sulfide and ammonia as bacteria digest tissues.

Autolysis, on the other hand, refers to the self-digestion or breakdown of cells and tissues due to the body's own enzymes after death, without the involvement of bacterial action. Decomposition is a broader term that encompasses all processes of decay, including both autolysis and putrefaction, while decantation is a physical separation process typically used in laboratory techniques and is unrelated to the biological breakdown of organic matter. Thus, the specificity of putrefaction to bacterial action makes it the correct answer in this context.