To find the ratio of children to keychains, we first determine the total number of keychains. Since there are six children and each child has two keychains, we calculate the total number of keychains as follows:
Total keychains = Number of children × Keychains per child = 6 × 2 = 12 keychains.
Now we can find the ratio of children to keychains:
Ratio of children to keychains = Number of children : Number of keychains = 6 : 12.
This ratio can be simplified by dividing both numbers by 6:
6 : 12 = 1 : 2.
Therefore, the correct response for the ratio of children to keychains is 6:12 or "ratio of 6 to 12."