**Core Concept**
Ocular muscles refer to the extraocular muscles responsible for controlling eye movements. These muscles can be affected by various pathogens, including parasites, which can lead to orbital infections or inflammation.

**Why the Correct Answer is Right**
Trichinella is a parasitic nematode that can infect the ocular muscles, particularly the extraocular muscles, leading to trichinosis. This condition can cause symptoms such as diplopia (double vision), ptosis (drooping eyelid), and eye pain. Trichinella larvae can penetrate the muscle tissue and cause inflammation, leading to the aforementioned symptoms.

**Why Each Wrong Option is Incorrect**
**Option B:** Ascaris is a large roundworm that primarily infects the small intestine and can cause intestinal obstruction or respiratory symptoms if it migrates to the lungs. It is not typically associated with ocular muscle infection.
**Option C:** Enterobius, also known as pinworms, primarily infect the large intestine and can cause perianal itching. They are not typically associated with ocular muscle infection.
**Option D:** None is incorrect because Trichinella can indeed infect the ocular muscles.

**Clinical Pearl / High-Yield Fact**
When evaluating patients with suspected ocular muscle weakness or pain, consider the possibility of Trichinella infection, especially in individuals who have consumed undercooked or raw meat, such as pork.

✓ Correct Answer: A. Trichinella