In a practical examination, the below given pedigree chart was given as spotter for identification. The students identified the pedigree chart as ____

If the trait were sex-linked recessive, the affected mother in generation I would have only affected sons. Since she has an unaffected son in generation II, it is not sex-linked recessive.

The trait appears in all generations, indicating a dominant trait. Assuming it is autosomal dominant, let the affected allele be $A$ and the normal allele be $a$.

The affected female in generation I must be heterozygous ($Aa$) because she has unaffected offspring ($aa$). Her unaffected partner is $aa$.

The cross $Aa \times aa$ produces both affected ($Aa$) and unaffected ($aa$) offspring, which matches the observed progeny in generation II.

Similarly, the affected female in generation II ($Aa$) and her unaffected partner ($aa$) produce both affected ($Aa$) and unaffected ($aa$) offspring in generation III, consistent with the pedigree.

This is a classic textbook pedigree for an autosomal dominant trait like myotonic dystrophy.

Answer: Autosomal dominant