Answer: Choice D
Step-by-step explanation:
The ratio 35:21 fully reduces to 5:3 after dividing both parts by the GCF 7.
35/7 = 5
21/7 = 3
Or put another way, the ratio 5:3 scales up to 35:21 after multiplying both parts by 7. Because of these equal ratios, the two rectangles are considered similar.