Final answer:
The term defined as a comparison between two quantities is a Ratio (C). Ratios fundamentally express the relationship between two quantities in mathematics and science, and are critical for understanding concepts in calculus, like derivatives, and in other areas like growth rates and acceleration.
Step-by-step explanation:
Ratio. A ratio is used to express how one quantity is related to another, providing a relative measure of two quantities. For example, when we look at calculus and the operation of taking derivatives, we are often dealing with ratios. Calculus itself is the mathematics of change, which takes ratios into account when dealing with rates, slopes, and growth rates, making the concept of ratio essential.
Ratios can be found in various scientific and mathematical concepts, from the slopes of graphs representing equations, such as supply and demand curves, to the change in velocity over time, which relates to acceleration. They are fundamental in understanding the relationship between different physical quantities, and their dimensions are expressed as ratios, for instance, in derivatives. Ratios are versatile and can also appear as fractions or percentages, providing a broad utility in mathematical representations.