Final answer:
Scientists prefer to use the metric system because it simplifies conversions by utilizing factors of 10. The metric system is the basis for the International System of Units (SI), which is used worldwide in science.
Step-by-step explanation:
Scientists prefer to use the metric system because it is based on factors of 10 and is easy to work with, hence the answer is a. metric.
The metric system's main advantage is that every unit increases by a factor of ten, which simplifies conversions. In the context of international standards for scientific measurements, the metric system forms the basis of the International System of Units (SI).
The SI Base Units include measures of length (meters), mass (kilograms), and time (seconds), among others. This system was established in France in 1795 and later adopted globally following the agreement in 1960, becoming an international standard for measurements in science.