Here we have that the biggest angle AOD can be written as sums of different angles:
The transitive property of the equality says that if:
In our case we have:
So according to the property:
And if:
Then we have that:
This means that you can prove the statement "if mAOB=mCOD then mBOD=mAOC" by using the transitive property of the equality. Therefore, the correct option is D.