What is the primary characteristic of Acromelia?

Acromelia is characterized primarily by the shortening of the distal parts of the limbs, specifically the hands and feet. This condition is often a result of a disproportionate reduction in the growth of the long bones during development, leading to a mesomorphic body shape where the torso is of normal length, but the extremities, particularly the hands and feet, are shorter than average.

The choice indicating "short hands and feet" correctly identifies this primary characteristic, as individuals with acromelia distinctly exhibit diminished size in these areas while the proximal portions of the limbs may maintain relative normalcy.

Other options represent conditions or characteristics that differ significantly from acromelia. For example, absent limbs pertains to a more severe malformation and is not a hallmark of acromelia. The option referring to all long bones being shortened or small does not specifically capture the selective nature of acromelia where the extremities are primarily affected. Syndactyly, which involves the fusion of fingers or toes, relates to a different congenital condition and is not a defining aspect of acromelia. Thus, short hands and feet accurately explain the key feature of acromelia.