Is this for math or science.? Because for math it should be d. Ratio in math means the the “quantitative relation between two amounts showing the number of times one value contains or is contained within the other” for example. The ratio of bananas to apples is 8 to 4.
But it is also used to describe the change of something. For example, the ratio that one say we will have floating cars is….
SO it most likely d. But maybe a. But I confused why there are science things.