How many instruments are mentioned in the passage

A．Aspirin has side effects on the stomach.
B．Aspirin can reduce fever.
C．The inventor of Aspirin lived in Greece.
D．One can use Aspirin to kill himself.

A．Aspirin: the Most Popular Medicine in the World
B．Why I Take Aspirin
C．The Side Effects of Aspirin
D．How to Take Aspirin