**Core Concept**
Sporothrix schenckii is a dimorphic fungus that causes sporotrichosis, a chronic fungal infection primarily affecting the skin. The organism is typically acquired through cutaneous inoculation.

**Why the Correct Answer is Right**
The skin is the primary portal of entry for Sporothrix schenckii. This occurs when the fungus enters the body through cuts or scratches in the skin, often as a result of handling infected plant material. The organism then proliferates in the skin, leading to the characteristic skin lesions and nodules of sporotrichosis. The fungus is usually introduced into the body through direct contact with infected plant material, such as rose thorns or other thorny plants.

**Why Each Wrong Option is Incorrect**
**Option A:** The lymphatic system is not the primary portal of entry for Sporothrix schenckii, although it may be involved in the dissemination of the infection from the skin.
**Option B:** The respiratory tract is not typically involved in the initial infection with Sporothrix schenckii, although rare cases of pulmonary sporotrichosis have been reported.
**Option D:** The mouth is not a common portal of entry for Sporothrix schenckii, as the infection is usually acquired through skin contact with infected plant material.

**Clinical Pearl / High-Yield Fact**
Gardeners and individuals who work with soil or plants are at increased risk of acquiring sporotrichosis due to the potential for cutaneous inoculation with Sporothrix schenckii.

**✓ Correct Answer: C. Skin**