**Core Concept**
Dacryocystorhinostomy (DCR) is a surgical procedure that aims to restore the normal flow of tears from the eye into the nasal cavity by creating a new passage between the lacrimal sac and the nasal cavity. This procedure is often performed to treat nasolacrimal duct obstruction.

**Why the Correct Answer is Right**
During DCR, the surgeon creates a new opening between the lacrimal sac and the nasal cavity. The lacrimal gland is not directly involved in this procedure, but its secretions do flow through the nasolacrimal duct into the nasal cavity. By creating a new passage, the surgeon allows the tears to drain directly into the nasal cavity, bypassing the obstructed nasolacrimal duct.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the lacrimal gland itself is not the primary focus of DCR. The procedure is aimed at restoring the flow of tears from the lacrimal sac into the nasal cavity.
* **Option B:** This option is incorrect because the lacrimal sac is the structure that is directly involved in DCR, but it is not the structure that the lacrimal gland opens into.
* **Option D:** This option is incorrect because the canaliculi are small tubes that collect tears from the eye and transport them into the lacrimal sac, but they are not the destination of the lacrimal gland's secretions.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that DCR is a surgical procedure aimed at restoring the normal flow of tears from the eye into the nasal cavity, bypassing the obstructed nasolacrimal duct. This procedure is often performed to treat nasolacrimal duct obstruction and is usually effective in improving tear drainage.

**Correct Answer: C. Nasal cavity.**