**Core Concept**
Retts disease is a rare neurodevelopmental disorder that affects brain development, leading to severe impairments in communication, social interaction, and motor skills. It primarily affects young girls, with a female-to-male ratio of approximately 3:1.

**Why the Correct Answer is Right**
Retts disease is caused by mutations in the MECP2 gene, which is located on the X chromosome. This gene plays a crucial role in brain development, and mutations in MECP2 lead to abnormal brain function and development. The X-linked inheritance pattern of Retts disease explains why it predominantly affects females, as they have two X chromosomes and are more likely to inherit two copies of the mutated gene. In contrast, males have only one X chromosome and are more likely to be affected by X-linked recessive disorders.

**Why Each Wrong Option is Incorrect**
**Option A:** Autism is a neurodevelopmental disorder that affects both males and females, with a male-to-female ratio of approximately 4:1. While females with autism may be underdiagnosed, it is not exclusive to females.
**Option B:** Asperger's syndrome is a neurodevelopmental disorder that affects individuals with average or above-average intelligence, often characterized by difficulties in social interaction and repetitive behaviors. Like autism, it affects both males and females.
**Option D:** There is no well-documented medical condition known as "Colard'd disease." It's possible that this is a distractor or a made-up option.

**Clinical Pearl / High-Yield Fact**
Retts disease is a classic example of an X-linked recessive disorder, which can help students understand the genetic basis of neurodevelopmental disorders and the importance of considering sex-linked inheritance patterns in diagnosis.

**✓ Correct Answer: C. Retts disease**