Step 1: Analyze the idiom's origin.
The idiom stems from military history, referring to capturing a Turkic/Tatar warrior, only to find that the captive is so fierce and unyielding that the captor is the one actually in trouble.
Step 2: Identify the modern usage.
Today, it means encountering an unexpectedly strong, stubborn, or difficult opponent or problem. Option (B) captures this precise meaning.