**Core Concept**
A 60-year-old man presenting with an ulcer on the lateral aspect of the tongue is likely to have a condition affecting the mucosal surface, possibly due to trauma, infection, or underlying disease process. The correct diagnosis involves identifying the specific cause of the ulceration, which may be related to the patient's age, medical history, and habits.

**Why the Correct Answer is Right**
The most common cause of ulcers on the tongue, especially in elderly individuals, is a fissured tongue or a geographic tongue. However, the presence of a lateral tongue ulcer in a 60-year-old man may also suggest a **cancerous etiology**, such as squamous cell carcinoma. This diagnosis is more likely if the ulcer is persistent, painful, and has irregular borders.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is likely incorrect because ulcers on the tongue are not typically caused by viral infections like herpes simplex virus.
* **Option B:** This option is unlikely because aphthous ulcers are more common on the oral mucosa, particularly on the buccal mucosa, and tend to be painful.
* **Option C:** This option is incorrect because a fissured tongue or geographic tongue typically presents with multiple, shallow ulcers and is often associated with vitamin deficiencies.

**Clinical Pearl / High-Yield Fact**
A persistent, painful ulcer on the lateral aspect of the tongue in a 60-year-old man should raise suspicion for squamous cell carcinoma, and further diagnostic workup is necessary to rule out this potentially life-threatening condition.

**Correct Answer:** D.