Among living organisms, which one of the following is the most responsible factor for bringing about the origin of a new species?

The Mutation is the most responsible factor for the origin of a new species because it is the ultimate source of genetic variation. According to the Mutation Theory proposed by Hugo de Vries, new species can arise through sudden, large genetic changes rather than just the gradual accumulation of small variations.

• Mutation: Creates new traits and alleles, providing the raw material for evolution.
• Natural Selection: Determines which traits are advantageous for survival, driving the adaptation of a species.
• Isolation: A critical mechanism for speciation that prevents interbreeding between populations, allowing them to evolve into distinct species.

While isolation and natural selection are essential to the evolutionary process, mutation is the fundamental factor that initiates the "origin" of the new genetic forms that define a species.