The answer is B, because we are learning about the national air and space museum, not the there museums.
I would say flighty is the correct one<span />
It takes the place of a noun
Use it describing the way someone rode something. "But Tait had none of Tillotson's gentleness, and he rode roughshod over the obstacles in his way." (That sentence is from yourdictionary.com by the way :) )
