Hello there!
Your answer would be D) 7:3
To write a ratio, you would have to order the ratio with the information provided in the question, respectively.
In your question, it says, "Which ratio can be used to compare the yellow marbles to the blue marbles"
From that information, we are comparing the yellow marbles to the blue marbles.
Since we have to put the ratio in respectively, the number of yellow marbles goes on the left side of the ":" and the number of blue marbles goes on the right side.
The number of yellow marbles: 7
The number of blue marbles: 3
Now we would put them into a ratio.
Ratio:
7:3