Answer: D
I65.21 code is appropriate for this case because it codes for occlusion and stenosis of the right carotid artery which is the diagnosis in this patient.
Option A is not correct because the I65.01 code is used for occlusion and stenosis of the right vertebral artery.
Option B is not correct because the I65.9 code is used for occlusion and stenosis of the unspecified precerebral artery.
Option C is not correct because the I65.22 code is used for occlusion and stenosis of the left carotid artery.