Read the selection and choose the best answer to each question that follows.

Frederic Tudor: America's Ice King

What could be more refreshing on a hot day than an iced drink? To most of us, ice-cold drinks seem normal. But for people living in a warm climate in the early 1800s, such a thing was not possible. Refrigeration had not yet been invented. Ice was simply not availableuntil a Massachusetts businessman named Frederic Tudor found a way.

The selection says, "His family believed in education and thought college was de rigueur." In this sentence, the phrase de rigueur means

A. strictly required.

B. very expensive.

C. pure nonsense.

D. very entertaining.