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
Which of the following perinatal infections has the highest risk of fetal infection in the first trimester: 
Select and explain. 
A. Hepatitis B virus, B. Syphilis, C. Toxoplasmosis, D. Rubella
D: Rubella
Answer: D: Rubella 
Explanation: None