No. of cusps in mandibular 1st molar:

**Core Concept**
The **mandibular first molar** is a key tooth in the lower jaw, playing a crucial role in mastication. Its structure, including the number of **cusps**, is essential for dental anatomy. Typically, the cusps of a tooth are the raised points on the chewing surface.

**Why the Correct Answer is Right**
The correct answer is based on the standard anatomical configuration of the **mandibular first molar**, which usually has five cusps. These include three buccal cusps (mesio-buccal, centro-buccal, and disto-buccal) and two lingual cusps. This arrangement facilitates efficient food breakdown.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it underrepresents the typical number of cusps.
**Option B:** Similarly, this option is too low for the standard anatomy of a **mandibular first molar**.
**Option D:** This option overestimates the usual number of cusps found on a **mandibular first molar**.

**Clinical Pearl / High-Yield Fact**
Remembering that the **mandibular first molar** typically has five cusps is crucial for dental restorations and understanding occlusal relationships. This knowledge helps in diagnosing and treating dental issues related to the lower molars.

**Correct Answer:** C. 5