Okay, let's tackle this question about the percentage of distal roots in mandibular molars that have two canals. First, I need to recall the anatomy of mandibular molars. Mandibular molars typically have two roots: mesial and distal. The mesial root usually has two canals, while the distal root is more variable.

The core concept here is the root canal morphology of mandibular molars, specifically the distal root. The key point is that while the mesial root is more predictable, the distal root can have one or two canals. I remember that the distal root of a mandibular molar has a higher chance of having two canals, but what's the exact percentage?

Now, the correct answer is likely around 25-30% because I think I've read that about 25% of distal roots in mandibular molars have two canals. But wait, some sources might say 30% or even up to 40%. Let me verify. From what I recall, the typical percentage is around 25-30%. So if the options are A. 25%, B. 30%, C. 40%, D. 50%, then the correct answer would be either A or B. However, the exact percentage might vary slightly based on different studies.

The incorrect options would be percentages that are too high or too low. For example, 50% is too high because most distal roots have one canal. The 40% might be a distractor from some studies, but the commonly accepted figure is lower. The 25% is a classic number often cited in dental textbooks. So the correct answer is probably 25% or 30%, depending on the source.

In terms of clinical pearl, it's important for endodontists to be aware of this variability because missing a second canal in the distal root can lead to persistent infection. Using a periapical radiograph and careful exploration are essential.

Putting this all together, the explanation should state that 25-30% of distal roots in mandibular molars have two canals, making the correct answer the one in that range. The other options are incorrect because they don't reflect the typical anatomical variation.

**Core Concept**
The distal root of mandibular molars exhibits variable root canal morphology. Clinically, it is crucial to identify the presence of 2 canals in the distal root due to its anatomical variability, which impacts endodontic treatment planning.

**Why the Correct Answer is Right**
Approximately **25–30% of distal roots in mandibular molars** contain 2 root canals. This variation arises from the developmental fusion of two separate Hertwig’s epithelial root sheaths. The second canal is often located on the **lingual side** of the root and may be missed during instrumentation without proper radiographic evaluation or tactile exploration.

**Why Each Wrong Option is Incorrect**
**Option A:** 50% is incorrect—most distal roots (70–75%) have a single canal, not 50%.
**Option B:** 10% is incorrect—this underestimates the prevalence of

✓ Correct Answer: B. 30%