Answer:
D1, O6, G7, O7
Explanation:
These are the answer because if you look at the graph every column spells GOOD. So in order to continue the pattern you must fill in the blanks with the correct letters to spell GOOD and the correct number for the column. Because each column has it's own number. So find the correct Letter-number pair! :)
HOPE THIS HELPED! HAVE A GREAT DAY!! :)