**Core Concept**
Acute anterior uveitis is an inflammatory condition affecting the anterior segment of the eye, characterized by pain, redness, watering, and photophobia due to inflammation of the iris and ciliary body. It is often associated with systemic conditions or can be idiopathic.

**Why the Correct Answer is Right**
The symptoms described for Lallo, such as pain, redness, watering, and intolerance to light, are classic for acute anterior uveitis. This condition occurs due to the inflammation of the iris and ciliary body, which can lead to the release of various chemical mediators, including histamine, serotonin, and bradykinin, causing pain and photophobia. The inflammation can also lead to the formation of aqueous humor flare, which is a key diagnostic feature of acute anterior uveitis.

**Why Each Wrong Option is Incorrect**
**Option A:** Keratitis typically presents with symptoms such as blurred vision, eye pain, and a foreign body sensation, but it is not as commonly associated with photophobia and aqueous humor flare as acute anterior uveitis.

**Option C:** Acute posterior uveitis primarily affects the retina and choroid, and its symptoms include blurred vision, floaters, and eye pain, but it is less likely to present with photophobia and aqueous humor flare.

**Option D:** Simple glaucoma typically presents with symptoms such as blurred vision, eye pain, and a red eye, but it is not typically associated with photophobia and aqueous humor flare.

**Clinical Pearl / High-Yield Fact**
Acute anterior uveitis can be associated with various systemic conditions, including ankylosing spondylitis, Behçet's disease, and sarcoidosis, so a thorough systemic evaluation is essential in the diagnosis and management of this condition.

**Correct Answer:**
✓ Correct Answer: B. Acute anterior uveitis