Step 1: Understanding the meaning of "Plausible"
"Plausible" means something that appears to be reasonable or believable based on available evidence.
Step 2: Analyzing the options
Option (A) "Impossible" means something that cannot happen, which is the opposite of "plausible."
Option (B) "Believable" is the correct answer, as it means something that can be accepted as true or reasonable, which aligns with "plausible."
Option (C) "Unlikely" refers to something that is not probable, but still possible, which is not the same as "plausible."
Option (D) "Unclear" means something that is ambiguous or not well-defined, which is not related to "plausible."
Thus, the correct answer is: (B) Believable.