**Core Concept**
The nasolacrimal duct is a crucial anatomical structure responsible for draining tears from the eye into the nasal cavity. The correct opening point of the nasolacrimal duct is a vital piece of anatomical knowledge for ophthalmologists and general surgeons.

**Why the Correct Answer is Right**
The nasolacrimal duct opens into the inferior meatus of the nasal cavity, which is the lowest part of the nasal passage. This anatomical arrangement allows tears to drain from the eye into the nasal cavity, preventing excessive tear accumulation and promoting a healthy ocular surface. The opening of the nasolacrimal duct is facilitated by the valve of Hasner, a mucosal fold that helps to regulate tear flow.

**Why Each Wrong Option is Incorrect**
* **Option A:** Incorrect because the nasolacrimal duct does not open into the nasopharynx. The nasopharynx is a higher part of the respiratory tract that is not directly associated with tear drainage.
* **Option B:** Incorrect because the nasolacrimal duct does not open into the maxillary sinus. The maxillary sinus is a paranasal sinus that is not directly connected to the nasolacrimal duct.
* **Option C:** Incorrect because the nasolacrimal duct does not open into the Eustachian tube. The Eustachian tube is a separate anatomical structure that connects the middle ear to the nasopharynx.

**Clinical Pearl / High-Yield Fact**
To remember the correct opening point of the nasolacrimal duct, recall that it opens into the inferior meatus, which is the lowest part of the nasal passage. This is a critical anatomical landmark for ophthalmic and nasal surgeons.

**Correct Answer: D. The inferior meatus of the nasal cavity.**