**Core Concept**
The pedigree represents a family with a genetic disorder, and the mode of inheritance needs to be determined based on the pattern of affected individuals and their relatives. Autosomal dominant, autosomal recessive, X-linked dominant, and X-linked recessive inheritance patterns can be distinguished based on the sex distribution and family history of the disorder.

**Why the Correct Answer is Right**
The pedigree shows an affected male and female in each generation, with all affected individuals having a family history of the disorder. This pattern is consistent with an autosomal dominant inheritance pattern, where a single copy of the mutated gene is sufficient to cause the disorder. The affected individuals in each generation are equally likely to be male or female, and there is no evidence of a sex-specific pattern of inheritance.

**Why Each Wrong Option is Incorrect**
**Option A:** Autosomal recessive inheritance would typically show a more sporadic pattern of affected individuals, with a higher frequency of affected individuals in consanguineous marriages. In this pedigree, the affected individuals are more common and evenly distributed across generations, making autosomal recessive inheritance less likely.
**Option B:** X-linked dominant inheritance would typically show a higher frequency of affected females, as they have two X chromosomes and one copy of the mutated gene is sufficient to cause the disorder. In this pedigree, there is no sex-specific pattern of inheritance, making X-linked dominant inheritance less likely.
**Option C:** X-linked recessive inheritance would typically show a higher frequency of affected males, as they have only one X chromosome and a single copy of the mutated gene is sufficient to cause the disorder. In this pedigree, there is no sex-specific pattern of inheritance, making X-linked recessive inheritance less likely.

**Clinical Pearl / High-Yield Fact**
When analyzing a pedigree, look for a consistent pattern of affected individuals and their relatives. Autosomal dominant disorders typically show a more uniform distribution of affected individuals across generations, whereas autosomal recessive disorders may show a more sporadic pattern. X-linked disorders may show a sex-specific pattern of inheritance, with a higher frequency of affected males or females.

**Correct Answer:** A. Autosomal dominant inheritance.