**Core Concept**
The **free gingival graft** is a surgical procedure used to increase the amount of attached gingiva around teeth, typically obtained from the **palate**. This procedure relies on the principle of **wound healing** and **tissue regeneration**. The ideal thickness of the graft is crucial for its success.

**Why the Correct Answer is Right**
The ideal thickness of a free gingival graft is around **0.8 to 1.5 mm**, as it allows for adequate **blood supply** and **nutrient diffusion** to the graft, promoting **healing** and **integration** with the recipient site. A graft of this thickness can be easily obtained from the **palatal mucosa** without compromising the **donor site**.

**Why Each Wrong Option is Incorrect**
**Option A:** Too thin, may not provide sufficient **tissue mass** for adequate **healing**.
**Option B:** Too thick, may compromise the **blood supply** to the graft.
**Option D:** Exceeds the ideal range, potentially leading to **graft failure**.

**Clinical Pearl / High-Yield Fact**
The key to a successful free gingival graft is careful **case selection**, **precise surgical technique**, and **post-operative care**. Remember, the **palatal mucosa** is the preferred **donor site** due to its **thickness** and **keratinized tissue**.

**Correct Answer:** C. 0.8 to 1.5 mm