Select the synonym of
probable

Let's understand the meanings of the terms:
probable: Likely to happen or be true.

plausible (Synonym): Seeming reasonable, probable, or likely to be believed.

futile: Pointless or useless.

absurd: Wildly unreasonable, illogical, or inappropriate.

preposterous: Contrary to reason or common sense; utterly absurd or ridiculous.

Therefore, plausible is the closest synonym.