Which of these is equivalent to 0.1 in the metric system?

The correct answer is deci, as deci represents a factor of one-tenth (0.1) in the metric system. The prefix 'deci-' comes from the Latin word "decimus," which means tenth. This prefix is commonly used in various measurements, such as decimeters, where one decimeter is equal to 0.1 meters.

In contrast, the other prefixes denote different values: centi represents one-hundredth (0.01), milli represents one-thousandth (0.001), and micro represents one-millionth (0.000001). Understanding these prefixes and their corresponding values is crucial in the field of pharmacology and other scientific disciplines, as it allows for precise measurement and communication of quantities.