Richard, an engineer, supervises the construction of a new mountainside roadway. When the road collapses in a landslide due to faulty grading, Richard is sued by motorists and hikers injured in the collapse. As a professional, Richard is held to the same standard of care as

Select one:

a$.$ those injured in the collapse of the bridge.

b$.$ other engineers.

C$.$ ordinary persons.

d$.$ other professionals, including doctors, dentists, and lawyers.