Which of the following drug is reported to be able to prevent colon cancer

A．Bextra can be used in heart surgery.
B．4 percent of those given placebo had an adverse event.
C．Celebrex worked as well as aspirin to prevent colon cancer.
D．Celebrex doubled or even tripled deaths from heart attack, stroke or heart failure.

A．helping patients at hospitals by providing them with trained animals.
B．registering all the pet owners in the U. S.
C．selling and buying pets.
D．motivating people to have a more colorful life.