This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Gynaecology & Obstetrics
A woman in her first pregnancy repos that she smokes one pack of cigarettes a day. An ultrasound is ordered in the thiy second week of the pregnancy to evaluate for which of the following: 
Select and explain. 
A. Amniotic fluid volume, B. Fetal size, C. Fetal abnormalities, D. Fetal motion
B: Fetal size
Answer: B: Fetal size 
Explanation: Fetal size