If Neandertals were not ancestors of today’s Europeans, then they probably A.) Evolved into Australopithecines
B.) Went extinct
C.) Lived in South Africa
D.) Moved to North America

B.) Went extinct

Explanation:

Neandertals were a subspecies of the the ancestors of modern humans and they occupied Eurasia while they were alive up to 40,000 years ago.

It was originally thought that Europeans may have descended from them but this was found not to be true even though traces of their DNA exist in very small quantities in Europeans. Rather they went extinct due to multiple factors including possible conflict with modern humans.

the name of the theory is landmass theory.