Equivalent ratios are those ratios which are same that is on simplifying each of them, we will get the same answer.
A.
![(2)/(3) and (9)/(15) = (3)/(5)](https://img.qammunity.org/2019/formulas/mathematics/high-school/4gjw62jfzlmqum5eyt8pegrfllfkqgbmbk.png)
So they are not equivalent
B.
![(5)/(8) and (15)/(21) = (5)/(7)](https://img.qammunity.org/2019/formulas/mathematics/high-school/bri4i759v9inbsafqw7tfu5ojzarvbz9m4.png)
So they are not equivalent
C.
![(3)/(12) and (6)/(18) = (1)/(4) and (1)/(3)](https://img.qammunity.org/2019/formulas/mathematics/high-school/gbil21l01mv7gi4loxnu01dvgwq6ocgzh6.png)
They are not equivalent too.
D.
![(4)/(10) and (12)/(30) = (2)/(5) and (2)/(5)](https://img.qammunity.org/2019/formulas/mathematics/high-school/wa3oo53xw1fwunoh70i283za9na8hn61fs.png)
And they are equivalent. SO the correct option is D .