Final answer:
The most distinctive traits about the cold adaptation complex of Neanderthals concern their body and limb proportions, which include a stocky build and shorter arms and legs.
Step-by-step explanation:
The most distinctive traits about the cold adaptation complex of Neandertals are c. the body and the length of the arms and legs. Neanderthals had a stocky build with shorter limbs, which suited their adaptation to cold climates. Additionally, their cranial features such as an occipital bun, large brow ridges, and a large nasal cavity were key adaptations to cold environments. Neanderthals also displayed a unique pattern of wear on their large front teeth, believed to be due to chewing on materials like leather, and their postcranial bones suggest well-developed rotator cuff muscles, robust humeri, and a capability for throwing projectiles and using spears.