Which of the following conditions allows for arrest based on an admissible confession?

A voluntary confession of a felony offense is deemed admissible in court, which allows law enforcement to pursue an arrest based on such a confession. When someone confesses voluntarily, it implies that they have done so of their own free will, without coercion, intimidation, or improper influence by authorities. This aligns with legal standards that protect defendants from self-incrimination and ensure that any confession used against them in court is made under fair conditions.

In the context of the other options, confessions made under duress or obtained through illegal means, such as coercion or while violating an individual's rights, are typically considered unreliable and inadmissible. Similarly, a conditional confession might depend on the fulfillment of certain criteria and may also not be singularly reliable for an arrest warrant. Thus, the voluntary nature of the confession in this instance is key to its admissibility and the legality of the arrest that follows.