Okay, let's tackle this question. The patient is a child with seizures, multiple oval hypo-pigmented macules on the trunk, and sub-normal IQ. The question is asking for the probable diagnosis.

First, I need to recall conditions that present with seizures, hypopigmented skin lesions, and intellectual disability. The key here is the combination of these symptoms. Hypopigmented macules that are oval and multiple could point to a specific syndrome.

Tuberous sclerosis comes to mind. It's a genetic disorder characterized by benign tumors in various organs, and one of the skin findings is hypomelanotic macules, often called "ash-leaf" spots. These are typically present from birth and are a hallmark sign. The seizures and intellectual disability are also common in tuberous sclerosis. The macules are usually located on the trunk or limbs, which matches the description here.

Other possibilities might include incontinentin, but that's more associated with incontinentin syndrome, which includes hypopigmented patches and other features. However, incontinentin is more about incontinence of melanin, leading to irregular patches, not oval. Neurofibromatosis type 1 has café-au-lait spots, which are hyperpigmented, not hypo. So that's not a match here.

Another thought could be Sturge-Weber syndrome, but that's associated with port-wine stains and seizures, but not hypopigmented lesions. Also, the intellectual disability in Sturge-Weber is usually due to the cerebral involvement, but the skin lesions are different.

So the most likely diagnosis here is tuberous sclerosis. The combination of seizures, hypopigmented macules, and intellectual disability fits this condition. The correct answer should be the option corresponding to tuberous sclerosis.

**Core Concept**
This question tests recognition of **tuberous sclerosis complex (TSC)**, a genetic disorder characterized by benign tumor growth in multiple organs, including the brain and skin. Key diagnostic features include **hypopigmented "ash-leaf" macules**, **epileptic seizures**, and **intellectual disability**. The diagnosis relies on clinical criteria (e.g., major/minor features) and genetic testing.

**Why the Correct Answer is Right**
TSC is caused by mutations in *TSC1* (hamartin) or *TSC2* (tuberin) genes, leading to dysregulated mTOR signaling and abnormal tissue growth. **Hypopigmented macules** on the trunk (ash-leaf spots) are classic skin findings. **Seizures** occur due to cortical tubers, while **intellectual disability** results from brain involvement. The triad of seizures, skin lesions, and cognitive impairment is diagnostic in this context.

**Why Each Wrong Option is Incorrect**
**Option A:** Neurofibromatosis type 1 (NF1) presents with café-au-lait spots (hyperpigmented), neurofibromas, and Lisch nodules—not hypopigmented lesions.
**Option B:** Incontinentia pigmenti is an X-linked disorder with linear hypopigmented/hyperpigmented skin lesions and dental abnormalities, but seizures and IQ deficits are not central features.
**Option C:** Sturge-Weber syndrome involves port-wine stains, leptomeningeal angiomatosis, and seizures

✓ Correct Answer: C. Tuberous Sclerosis