In this task, You are given an open-domain question that can be answered based on factual information. Your task is to provide \*short\* answer (in a few words only) for the given question. The short answer can be one or more entities or it can also be boolean \*yes\* or \*no\*.

who took the picture of the windows xp background
Charles O'Rear

who led an expedition to explore the louisiana territory
Lewis and Clark

the free surface of a rotating fluid is

a paraboloid