Final answer:
The most very large theropods with short necks and small forelimbs were the carnosaurs, which makes option A the correct answer. These dinosaurs were known for their large size and predatory nature.
Step-by-step explanation:
The most very large theropods with short necks and small forelimbs were the carnosaurs. These creatures, part of the Saurischia (“lizard-hipped”) dinosaurs, were characterized by their large size and predatory nature. The carnosaurs include well-known genera such as Allosaurus and Giganotosaurus. Although some theropods like the famous Tyrannosaurus rex are also large with small arms, they are part of a different group called coelurosaurs. When considering theropods with the specific features mentioned, namely very large size, short necks, and small forelimbs, carnosaurs are the appropriate group to identify.
Answer choice A, carnosaurs, fits the description given in the question and is the correct answer. Choices B, coelurosaurs, C, tetanurans, and D, allosaurids, although related, do not match the criteria as tightly as the carnosaurs.