Scientists once believed that Tyrannosaurus rex dragged its tail along the ground. Today, they know that T. rex did not drag its tail but held it aloft, above the ground. This change in scientific consensus happened because
a. scientists liked the idea that T. rex held its tail aloft better.
b. no one supported the idea that T. rex dragged its tail on the ground.
c. the idea that T. rex held its tail aloft is an emerging idea that replaced the old idea.
d. the idea that T. rex held its tail aloft was supported by the studies of many scientists.