**Core Concept:** Operation theatre fires occur due to the combination of flammable materials, oxygen, and an ignition source. The most common causes include sparks from surgical instruments, electrical surges, and improperly extinguished cigarettes or lit materials.

**Why the Correct Answer is Right:** The correct answer (C) is related to the key factors contributing to operation theatre fires. The presence of flammable materials such as drapes, linens, and human skin can easily catch fire when exposed to an ignition source like sparks from surgical instruments (Option A), electrical surges (Option B), or the combination of these factors (Option D).

**Why Each Wrong Option is Incorrect:** Option A focuses on surgical instruments as the sole cause of ignition, but fires can result from various sources like electrical surges (Option B) or cigarette smoking (Option D). Option C addresses the combination of these factors, which is more likely to lead to an operation theatre fire.

**Clinical Pearl:** Proper theatre safety measures include using fire-retardant materials, ensuring electrical systems are safe, and enforcing smoke-free policies in operating rooms.

**Correct Answer:** **C.** Combination of ignition sources like surgical sparks and flammable materials present in the operating room.