Select the real-world problem that could be solved using a proportion.
A Sheila has 3 pens and 7 pencils. How many more pens does she need to make the number of pens and pencils she has equivalent?
B Sheila has 2 dogs and adopts 2 more. How many dogs does she have in total?
C Sheila must pay $90 for a phone and then $30 each month for service. How much will she have paid after 7 months?
D Sheila travels 90 miles in 3 hours. At this rate, how far will she travel in 7 hours?
