To find the ratio of the constant of proportionality, we need to determine the relationship between the number of pages read and the time it takes.
Given that Ruth can read 15 pages in 30 minutes, we can set up the following proportion:
15 pages / 30 minutes = K, where K is the constant of proportionality.
To simplify this proportion, we can divide both the numerator and denominator by 15:
1 page / 2 minutes = K
Therefore, the correct ratio for the constant of proportionality is C: (15, 1/2).