A proportion is two or more parts, share or numbers that are considered comparative relation to a whole.
Basically, when you have two fractions, 2/4 and 3/6 for example, they will equal the same amount even if their numbers are different. Normally, we would reduce both of these fractions to 1/2 because 2 is 1/2 of 4 and 3 is 1/2 of 6.
With this information you should be able to figure out which choices are proportionate and which isn't. (hint** only one answer isn't proportionate)