Write the following sentence as a proportion.

12 diamonds is to 9 opals as 4 diamonds is to 3 opals.
Choose the correct answer below.
A. 9 opals/12 diamonds = 3 opals/4 diamonds
B. 12 opals/9 diamonds = 4 opals/3 diamonds
C. 12 diamonds/9 opals = 3 diamonds/3 opals
D. 9 diamonds/12 opals = 3 diamonds/4 opals

A. 9 opals/12 diamonds = 3 opals/4 diamonds

To write the given sentence as a proportion, we need to set up the ratio of diamonds to opals on both sides of the sentence.

The given information states that 12 diamonds is to 9 opals as 4 diamonds is to 3 opals.

So, we can write this proportion as:

12 diamonds/9 opals = 4 diamonds/3 opals

To find the correct answer choice, we can rewrite the proportion in terms of diamonds/opals as:

9 opals/12 diamonds = 3 opals/4 diamonds

Therefore, the correct answer is:

A. 9 opals/12 diamonds = 3 opals/4 diamonds

The correct answer is A. 9 opals/12 diamonds = 3 opals/4 diamonds.