pls what is the correct answer:

Ruth can read 15 pages in 30 minutes. She decides to create a table to keep track of her progress. From the data provided, at what ratio is the unit rate (constant of proportionality) represented?
Time(hours) 1/2, 1, 1 1/2, 2
pages read 15, 30, 45, 60
(2, 60)
(2, 60)

(1, 30)
(1, 30)

(12, 15)
(12, 15)

(15, 30)