A 35 year old mother carrying twin gestations, who has a three year old child with Down syndrome, comes in for a prenatal screening. She is in her 12th week of pregnancy and the physician requests that the amount of fluid behind the necks of the fetuses be measured. A transabdominal approach was used. Which is the correct code(s)?

A. 76801, 76802
B. 76811, 76812
C. 76813, 76814
D. 76816, 76816-59