On the average, the Neanderthals were physically:

a. taller and thinner than modern humans

b. much more lightly built than modern humans

c. shorter and more muscular than modern humans

d. probably weaker than modern humans

e. more similar to the gracile (smaller) australopithecines than to modern humans

The correct answer will be option C - shorter and more muscular than modern humans.

Explanation:

Neanderthals were a species of genus Homo which resembles the humans but they were distinct species that is Homo nendethaliensis. They were our closest ancestors which co-existed with the humans but became extinct around 10,000 years ago.

The fossils of the neanderthals showed that they can be easily distinguished from modern humans as they were more muscular and had strong bodies than modern humans. Their body was stocky that is with shorter legs as an adaptive feature to cold climate.

Thus, option C is the correct answer.