* Polyploidy: This is the condition of having more than two sets of chromosomes. It can occur through errors in cell division (meiosis). A polyploid individual can no longer reproduce with its diploid ancestors, effectively creating a new species instantly.

Let's look at why the other options are incorrect:

* Habitat isolation: This involves physical separation of populations, which can lead to speciation over time as populations adapt to their different environments. It's not an instant process.

* Behavioral isolation: This involves differences in mating rituals or preferences that prevent individuals from different populations from interbreeding. This also takes time for these differences to develop and become significant barriers to reproduction.

* Genetic drift: This is the random fluctuation of allele frequencies in a population, especially significant in small populations. While it can lead to changes in traits and potentially speciation, it's a gradual process.

In summary: Polyploidy is the only option that can lead to instant speciation because it creates a reproductive barrier between the polyploid individual and its ancestral population.